TOJOIN 1 pcs SMA Torque Wrench for RF Connector 8 in·lbs (0.9 N·m) Opening 8mm (5/16") for SMA 3.5mm/2.92mm Adapter Convertor Portable Spanner for Professionals Industry Blue

If you only screw your SMA connectors hand tight, you will inevitably get grossly incorrect and inconsistent results! So, it is necessary to used a wrench to tighten SMA connectors. How tight? 6 in-lbs is good for consistent electrical connection, 8 in-lbs for permanent vibration proof connection.IMPORTANT - the wrench comes without lubrication! You must apply oil to the elbow and internal cylindrical sliding surfaces, and a heavy grease to the ball surface - else excess friction will probably break your SMA connector! Once the tool is properly lubricated, it should be re-calibrated using known weight and length scales. With all this done, an SMA connector can easily take 6 to 8 in-lbs. torque - no problem!Do not push on the end of the torque wrench handle! When applying torque, remember that you are literally "applying torque" - not linear force. This means your hand and wrist should impart a twisting action. If there is any linear force applied to the tool, it will result in a combined force (sheer + bending + torsion) when all that is needed is a simple torsional force. Unnecessary combined force could break or damage a SMA connector or PC board.4 out of 5 stars because the tool is quite a bit bigger than expected or needed, which makes it somewhat less convenient to use.--a mechanical engineer