Flex 24V Compact Impact Wrench Review

Flex Compact Impact Wrench

Flex Adds Two Compact Impact Wrenches To Its Growing 24V Lineup

Over the last few years, I’ve had the opportunity to get my hands on the majority of Flex’s 24V lineup. In terms of performance, they stand toe-to-toe with other Pro-grade brands without breaking a sweat, however, they’re noticeably larger and heavier. In light of this, Flex is expanding their 24V compact line, which now includes a 1/2-inch and 3/8-inch Compact Impact Wrench.


  • Multiple anvil sizes available
  • Adjustable LED work light brightness
  • Halo-style LED work light
  • Excellent performance during our testing


  • Slightly heavier than comparable models

Flex Compact Impact Wrench Performance

Flex Compact Impact Wrench profile
  • No-Load Speed: 0-1000/1800/2700 RPM
  • Impact Rate: 3750 IPM
  • Max Torque: 300 ft-lbs (fastening), 450 ft-lbs (breakaway)

When it comes to speed and power, I had pretty high expectations after our extensive testing with other Flex tools. The FX1431 and FX1431A are completely identical in terms of speed, impact rate, and torque. Both top out at 2,700 RPMs, 3,750 impacts per minute, 300 ft-lbs of fastening torque, and 450 ft-lbs of breakaway torque.

With this kind of specs, these tools are right in line with what we’ve come to expect from Pro-grade compact impact wrenches.

Speed and mode controls

These tools have three main speed settings and two specialty bolt modes. The “A” is a special mode that is designed to be used both with forward and reverse. In forward rotation, the impact wrench will stop running when the tool senses the bolt or nut is pre-tightened, preventing over-tightening. In reverse, the tool will stop rotation once the nut or bolt is loose to help prevent it from falling away.

The auto-stop mode comes in handy when removing lug nuts, or when working overhead, so you’re less likely to lose anything or injure yourself.

For top performance while driving lag bolts or other fasteners into wood, you’ll want to switch over to the “bolt” symbol. To do so, just tap the “M” button to toggle between modes.

Flex Compact Impact Wrench Design Notes

Flex Compact Impact Wrench
  • Model: FX1431A (3/8-inch), FX1431 (1/2-inch)
  • Power Source: Flex 24V battery
  • Weight: 2.6 lbs (bare), 4.2 lbs (with 3.5Ah battery), 4.75 lbs (with 5.0Ah battery)
  • Head Length: 4.8 in. (FX1431A), 4.9 in. (FX1431)

Looking at this tool, it’s clear that Flex set their sights on keeping it lightweight and compact, especially compared to their previous models. The Flex FX1431 weighs in at 2.6 pounds as a bare tool, 4.2 pounds with a 3.5Ah Stacked Lithium battery, and 4.9 pounds with a standard 5.0Ah battery.

The 1/2-inch model measures 4.9 inches from tip to tail and the 3/8-inch model is on a fraction of an inch shorter at 4.8 inches. These numbers put it right in line with the Flex FX1371A Impact Driver!

In general, I tend to enjoy the feel of Flex tools because of their robust and aggressive rubber overmold and how they contour nicely to my hands. In this case, they really haven’t strayed away from the formula. These compact impact wrenches feel pretty good in my medium size hands, giving me a lot of confidence that they won’t slip while working, even without work gloves.

360-Degree LED Light

One aspect I truly love about this impact wrench is the 360° LED work light. It provides better light coverage than a foot-mounted light and fully illuminates your workspace. Along with the halo style light, Flex made the brightness level adjustable so you can tailor it to your needs.

360-degree LED light

To adjust the brightness, press and hold the drive control and mode button for two seconds until the indicator lights start flashing. Next, pull the trigger to cycle through the six brightness settings, or you can shut off the light if you have sufficient lighting. When you’re finished, just press either button to exit the adjustment mode.

Additional Features

  • Compatible with all Flex 24V batteries
  • Tether ready for working at height
  • Two-position belt hook

Flex Compact Impact Wrench Price

These Flex 3/8-inch FX1431A retails for $179 as a bare tool and $239 as kit, that includes a 5.0Ah battery, charger, and storage bag. If you prefer a 1/2-inch anvil, the FX1431 is available as a kit for $249 and comes with a 3.5Ah Stacked Lithium battery, charger, and a storage bag.

The Bottom Line

Compared to their high-torque and mid-torque counterparts, the Flex Compact Impact Wrenches are noticeably lighter and more nimble. They are perfect for those light to medium-duty fastening applications where space is at a premium or a lighter tool simply proves advantageous. I can see these coming in handy around the garage or automotive repair shop if you’re looking to ditch the air hose or simply expand your tool arsenal. Granted, they aren’t as lightest or most compact models available, but they do deliver an impressive amount of muscle considering their size.

Related articles