The Munbyn RealWriter 405B label maker offers two attention-grabbing features. The first is a replaceable printhead that can extend the printer's life—a solid extra for a printer that costs $219.99. The second is two-color printing, using black in combination with either red or blue. However, a less-than-intuitive print app and limits on two-color printing hold it back. So while the RW405B doesn't replace either of our two current Editors' Choice picks for 4-by-6-inch label printing—the Rollo Wireless Printer X1040 and the Arkscan 2054A-LAN—it offers enough to make it a strong contender, particularly if you plan to print primarily from other apps besides Munbyn's.

Design: Engineered to Avoid Wasted Labels

Some desktop printers for 4-by-6-inch labels—including the 2054A—have room to mount a label roll inside the printer. Others, including both the RW405B and the X1040, don't. Typically, this means you need to reserve 7 or 8 inches of space behind the printer for a stack of fanfold labels or a label holder designed for stacks or rolls as needed.

A potential problem with leaving the labels outside of the printer is that if they aren't lined up just right, they can skew slightly as they go into the input slot, eventually creating paper jams or other issues. The RW405B addresses this by shipping with its own label holder. It's a separate piece that sits behind the printer, but it adds squat square pegs on two corners. The pegs fit into matching holes on the bottom of the printer, like Lego pieces, to keep the holder properly positioned. Place the stack or roll of labels on the holder, feed the leading label through the guides on the printer, and you're set. You'd have to work hard to misalign the labels.

(Credit: M. David Stone)

Even better, when you feed the leading label into the input slot, the printer mechanism grabs it, feeds the labels back and forth, automatically sets the feed to match the label length, and positions the first label precisely where it needs to be for printing. This is one of the few label printers I've tested that handled this task reliably and without wasting labels in the process. The more often you switch between rolls, the more you'll appreciate both the ease of loading new labels and being able to avoid wasting any.

The physical setup is complicated by having to snap the pieces of the stand together, but the steps are reasonably well explained in the Quick Start guide. The printer itself measures 2.9 by 8.2 by 3.5 inches (HWD). Adding the stand increases the depth to 11.5 inches.

(Credit: M. David Stone)

Software setup and connection options depend on what you're printing from and what you want to print. To sort out the choices, it helps to know that Munbyn Print is the name for both a mobile app for Android and iOS, as well as a cloud-based program that supports only two browsers: Microsoft Edge and Chrome. Using either the app or a browser, you can download more than 2,000 templates and 3,500 pieces of clip art, create a label, and store finished labels on either your device or in the cloud.

For Android and iOS devices, the only way to print is through a Bluetooth connection to the printer. For both Windows and macOS computers, however, you have several choices. To print from virtually any app on your computer, including one that prints PDF label files saved to disk. For example, you can download a driver for your OS from Munbyn, install it, and connect using either a Bluetooth or USB connection. To print labels from Munbyn Print, you can use the driver as well; however, it doesn't offer two-color support for USB connections, and Munbyn says it has no current plans to add it. Your other choice is to use a Bluetooth connection, which doesn't need a driver and adds support for dual-color printing.

(Credit: M. David Stone)

If you buy the RW405B, it's a good idea to order some labels at the same time. It ships with a short stack of 4-by-6-inch fanfold labels, but you'll run out of them quickly. Munbyn offers a variety of types, colors, and even shapes, in sizes from 1 by 2 inches to 4 by 6 inches, at prices that range from 1 to 11 cents per label. For 4-by-6-inch labels, for example, the cost ranges from 4 to 8 cents per label, with a choice of white, pink, blue, and brown for the color. The printer can also use polypropylene (PP) plastic labels and specialized labels for bakers that I discussed in more detail in our review of the Munbyn FM226.

(Credit: M. David Stone)

At the time of this writing, the company has only two rolls available for dual-color printing (though Munbyn says it's actively working on adding more options), and the RW405B is the only printer that can use them. Each roll—one for black and blue and one for black and red—has die-cut circular labels on a 2-by-2-inch square. The price per label works out to about 8.7 cents at list price, and less at current street prices. To print in two colors, you first define the color for each text and graphic element in the label in Munbyn Print. The app works with the printer firmware to control the temperature across the printhead, and the temperature at each spot determines whether the paper will turn black at that spot or either red or blue, depending on which roll you're using.

One nice touch that increases your label options is the ability to work with other brands' labels as well. According to Munbyn, the RW405B will accept any labels with a carrier paper width between 1.57 and 4.25 inches, while the stand can handle rolls up to 4 inches in diameter. For label rolls without gaps between labels, you can also set the feed length manually. You can also print on continuous receipt paper. Even better, the stand offers two concentric mounts for rolls—one for rolls with .5-to-1-inch diameter cores, and one for 1-inch or larger cores.

(Credit: M. David Stone)

Although the replaceable printhead can indeed help extend the printer's life, it may not do so in the way you'd think. The printhead is rated at 93.2 miles of printing per printhead, just shy of 1,000,000 6-inch long labels. Even if you print 100 labels per day, 20 workdays per month, it would take more than 40 years to print that many. The real benefit is that maintenance is key to printhead performance, and being able to remove it from the printer can make cleaning it easier. In addition, if it's damaged in any way, you can replace just the head rather than the entire printer. Munbyn expects the printhead to sell for between $30 and $40.

Performance: Fast Speed and Good-Looking Labels

For my timing tests, I connected the RW405B to our standard Windows testbed using a USB connection. For quality tests, I printed some labels the same way, and others from my Samsung S25 phone using Munbyn's mobile app.

The RW405B is the third printer I've reviewed that uses Munbyn Print, the other two being the Munbyn FM226 and RW402B. As I discussed in those reviews. I found Munbyn's mobile app easy to use for simple tasks, such as selecting a template to print, but difficult to learn. It also didn't help that some controls work differently in the online version than in the Android app.

(Credit: M. David Stone)

A big part of the problem is the documentation. For example, the User Guide's QR codes for tutorials all point to how-to videos that fly by so quickly, with jump cuts (and distracting music), that they're hard to follow. Among other frustrations, hitting pause so I could zoom in on some detail that's way too small to make out on a phone screen usually left me having to back up to find what I wanted to see. All that said, the program itself is reasonably capable if you're willing to take the time to learn it. (For more details, take a look at my descriptions of Munbyn Print in the FM226 and RW402B reviews.)

The RW405B's specs put its maximum speed at 150 millimeters per second (mm/sec), or 5.9 inches per second (ips), although its default setting, which I used for testing and is meant to deliver better quality, is only 100 mm/sec or 3.9ips. Printing 4-by-6-inch labels using our standard PDF test files and a USB connection, it averaged 4.1 seconds for a single label, 20.7 seconds for 10 labels, and 94.3 seconds for 50 labels, which works out to 3.2ips for 50 labels.

(Credit: M. David Stone)

In comparison, the RW402B was slightly slower, at 4.2 seconds for a single label, 21.5 seconds for 10, and 98.2 seconds for 50, which works out to the same 3.2ipm. The Rollo X1040 was slower for one label, at 7.1 seconds, but slightly faster for 50, at 90.8 seconds, or 3.8ips. The Arkscan 2054A-LAN was tested using an earlier generation test protocol with different label content (which affects speed), so we can't make a performance comparison between it and the other three models.

The RW405B's resolution is 203dpi, a common choice for label printers, and a high enough resolution to deliver suitably dark and readable output. The dual-color labels also deliver an eye-catching color boost for words you want to stand out, like "Fragile" or "This Side Up," in labels that you might add along with a shipping label.