A Jack Screw is simply a 3/16” Hex, 4-40 Male-Female Standoff, that is 3/16” in length. What separates these is that you can choose the male-thread length that will best fit your application. Also called Female Screw-Locks, they are most commonly used in mounting D-Sub Connectors to the circuit board. As each D-Sub connector requires 2 screws, each Jack Screw Bulk Kit contains 2 Screws, 4 Flat Washers, 2 Lock Washers and 2 Nuts. Each component comes bulk packaged for added cost savings. The hex shape allows for greater torquing as the flat sides allow for wrench tightening. Aluminum is widely used in Aerospace applications due to its high strength to weight properties. RoHS certifications available.