Whether you’re a seasoned Pro or a serious DIYer, having the right tool for applying caulk or adhesive can make all the difference in both speed and finish quality. Flex has introduced a trio of 24V caulk and adhesive guns tailored for different jobsite needs. While these three models may look similar at a glance, each one is purpose-built for a specific cartridge size and offer flexibility without compromising on power or performance. In this breakdown, I’m taking a closer look at what sets these models apart, where they shine, and why their interchangeable designs make them a standout in a crowded field.
Flex 24V Caulk and Adhesive Gun: Key Features
Flex released three models of this caulk and adhesive gun, and the actual power heads all look eerily similar…because they are! These tools sport three different model numbers, but the numbers correspond to the size of the tubes, which are available in 10, 20, or 29-ounce configurations.
The 10-ounce (FX6211) is compatible with the common caulk and adhesive tubes you’ll find on the shelf at your local hardware store. The other two are more geared towards the construction industry.
The 20-ounce model (FX6221) features what’s referred to as a “sausage-style” aluminum tube that uses soft adhesive pouches rather than the more traditional tube. This style is also compatible with bulk adhesive that is drawn directly into the tube using the suction created by the plunger. This model comes with three cone-shaped nozzles that can be trimmed to meet your needs.
Lastly, Flex’s 29-ounce model (FX6231) is designed for applying construction adhesives and other sealants. Since you’re dealing with a larger volume, having that battery-powered assist is an absolute Godsend for your weary hands.
Other than that, the power heads are completely identical and interchangeable.
Interchangeable Accessories
As I already mentioned, three configurations are available. But thankfully, buying all three models is unnecessary because the individual tubes and plungers are available separately.
Swapping the tubes only takes a few seconds, but removing the plunger requires you to remove the rear pull handle to allow the rod to pass forward through the motor housing. All in, the process takes about a minute from start to finish.
Granted, Flex certainly isn’t the first company to employ interchangeable tubes. However, it’s a smart play for this first-generation tool that immediately vaults Flex up with the best model from competing brands.
Size and Weight
Since these tools are designed for different applications, their weight and balance vary slightly. Here’s a quick spec breakdown of each model.
| FX6211 | FX6221 | FX6231 | |
|---|---|---|---|
| Tube Size | 10 oz. | 20 oz. | 29 oz. |
| Bare Weight | 4.6 lbs | 5.5 lbs | 5.1 lbs |
| Working Weight | 6.2 lbs | 7.1 lbs | 6.7 lbs |
| Length | 19 in. | 28 in. | 24 in. |
As of right now, Flex does not offer these applicators as a kit, but due to the nature of these tools, lighter weight is ideal. Considering that, we weighed them all with a 3.5Ah Stacked Lithium battery to get an optimal balance of power and weight. You could always go with a bigger battery to get more runtime, but in my experience, these tools don’t draw a ton of power, so a smaller battery works just fine.
Grip and Trigger
Looking down at the grip, these tools share a familiar form factor with the rest of Flex’s 24V lineup. They all feature a generous amount of textured rubber overmolding that extends across the tool body for added protection.
They feature a two-finger trigger, trigger lock, and an override button that allows you to manually adjust the plunger.
Flow Rate
The Flex 24V caulk guns feature six speed settings and a variable-speed trigger that allows them to dispense up to 33 IPM of material—a full 12 IPM more than the Milwaukee 2641 and DeWalt DCE560. The variable-speed dial establishes the maximum plunger speed, but you can always feather the trigger for added control.
These variable speeds let you dial in the precise flow rate that best suits your needs, but keep in mind that operating the motor at high speed may damage or rupture the tube. For best results, gradually increase the speed during the application process.
Anti-Drip Control
These caulking guns feature an automatic retraction system that prevents adhesive from dripping after shutdown. Once the trigger is released, the plunger rod automatically pulls back about 1/4-inch to relieve the pressure on the tube. If you’ve only ever used manual caulk guns, this will be an absolute game-changer for you.
Flex 24V Caulk and Adhesive Gun Price
These caulk guns cost between $199 and $229 and are currently only available as bare tools. A 5-year limited warranty backs all three models, but they’re also eligible for Flex’s limited lifetime warranty with registration within 30 days of purchase.
The Bottom Line
Whether you’re installing new windows, sealing your new drop-in shower, or simply laying down a smooth bead of caulk around your baseboards, undoubtedly, these Flex 24V caulk and adhesive guns make life easier. They deliver an impressive flow rate and a well-balanced profile that is sure to have your weary hands thanking you at the end of the day.
The best part about these tools is the versatility for Pros. Even though it’s not the first time we’ve seen interchangeable tubes and plungers, Flex made the whole process so easy, and that goes a long way in my book. We do wish they were available in a kit configuration, but if you’re already on Flex’s 24V platform, these are a no-brainer.
