Any 5/16" wrench for loosening. For tightening, ideally the appropriate torque wrench for the particular connector (material & grade) should be used. https://w

Any 5/16" wrench for loosening. For tightening, ideally the appropriate torque wrench for the particular connector (material & grade) should be used. https://www.centricrf.com/torque-wrenches/sma-torque-wrenches-screwdrivers/ https://www.centricrf.com/torque-wrenches/sma-torque-wrenche... Or other stores. RF connectors should be torqued to a specified torque listed on their data sheet. Improper torque can cause damage. Usually for equipment using SMA connectors this isn't a big deal (just replace the connector, they're cheap and the torque wrenches are expensive), but for the really high frequency stuff like 1.85mm connectors the connector itself is $70-300 so spending $100-400 on a torque wrench is reasonable.