3/8" diameter with recessed adjustable plunger from 1/4" to 1/2". Case made from nylon for durability and flexibility which resists locking problems caused by expansion and contraction. Stainless steel spring and sealed contact insure a long service life. 12" 22AWG leads. TS-20 has a screw down flange for positive retention. The TSC-20 has a clip mount for security panels and other alarm boxes. Lifetime Warranty. Made in the USA.