X-4 Tool Perf-A-Torq precision torque limiters convert any standard ratchet or socket drive tool to a torque limiting wrench

Perf-A-Torq™ precision torque limiters can be attached to any standard drive tool to provide the ultimate in torque control. Once the torque limit is set, The X-4 Tool Perf-A-Torq Torque Limiter prevents the applied force from exceeding the setting. When the preset torque value is reached the torque limiter releases with an audible ‘click’. Perf-A-Torq torque limiters may also be used in automated applications at speeds lower than 300RPM. Please note that Perf-A-Torq limiters are NOT recommended for use with impact type driving tools.

X-4 Tool Perf-A-Torq Torque Limiters are available in four standard sizes for use with 3/8" and 1/2" standard square drive tools, Perf-A-Torq limiters combine compactness and a unique resettable torque limit design to maintain precise torque control and accurate repeatability in any application where precision control is a necessity.

Special Applications - Custom Configurations

X-4 Tool Perf-A-Torq Torque Limiters are produced in a wide array of custom configurations engineered specifically to satisfy distinct customer requirements. Contact us with details related to your application and we will determine how to best resolve your precision torque limiting challenge.


X-4 Tool Perf-A-Torq™ Torque Limiters are ideal for use in a wide variety of applications where precise torque control is required. The unit's low cost makes it an ideal tool for repetitive assembly and production line torquing procedures.

  • Snaps onto any standard 3/8” or 1/2” square driving tool
  • X-4 Tool Perf-A-Torq Torque Limiters release with an audible ‘click’ when the preset torque limit is reached
  • Patented torque setting mechanism and locking feature insures precision control and repeatability
  • One-way limiters are available that release in one direction and lock in the other
  • Torque limits can be set either by the user or preset by the factory
  • Compact design allows Perf-A-Torq limiters to be used in areas where accessibility is restricted
  • High quality components and construction ensure durability
  • Six standard models are available for immediate delivery for torque capacities ranging from 24 to 1440 inch pounds (2 to 120 ft-lbs)
  • Can be set for metric torque measuring and control
  • All X-4 Tool Torque Limiters are 100% MADE IN THE USA
Torque Limiter Cross Section

Where possible, select a Perf-A-Torq™ model that meets the expected torque demands at approximately midrange.

Example: For torque values around 420 inch pounds, select model 12B with a range of 240 to 600 in-lbs, and midrange of 420 in-lbs.

Model Drive Sq.
Male & Female
Torque Limit (Min) Torque Limit (Max) Nominal Outside
"A" Dim. "B" Dim. Weight
38A 3/8" 24 in-lb 2.7 N-m 180 in-lb 20.3 N-m 1.6" 41 mm 1.7" 43 mm 2.2" 56 mm 12.5 oz 354 g
38B 3/8" 60 in-lb 6.8 N-m 300 in-lb 33.9 N-m 1.6" 41 mm 1.7" 43 mm 2.2" 56 mm 12.5 oz 354 g
12A 1/2" 120 in-lb 13.6 N-m 480 in-lb 54.2 N-m 1.7" 43 mm 1.9" 48 mm 2.7" 69 mm 17.5 oz 496 g
12B 1/2" 240 in-lb 27.1 N-m 600 in-lb 67.8 N-m 1.7" 43 mm 1.9" 48 mm 2.7" 69 mm 17.5 oz 496 g
12D 1/2" 480 in-lb 54.2 N-m 900 in-lb 101.7 N-m 2.2" 56 mm 1.9" 48 mm 2.7" 69 mm 1 lb 6oz 624 g
12E 1/2" 720 in-lb 81.4 N-m 1440 in-lb 162.7 N-m 3.0" 76 mm 2.0" 51 mm 2.9" 74 mm 3 lb 1.4 kg

Perf-a-Torq Torque Limiter Options - Call for Pricing

  • Option 1: Factory preset service available per tool.
  • Option 2: Model 38A, 38B, 12A, 12B, and 12E can be ordered with a clockwise torque control and counterclockwise lock. Suffix "-OW"
  • Option 3: Model 38A can be supplied with light torque setting as low as 10 inch pounds. The upper limit will be significantly lower than standard, suffix "/L".
  • Option 4: Certification with printout to NIST standards available, preset included.
  • Option 5: Custom modifications quoted on application.