These ST fiber couplers are compatible with both multimode and singlemode ST fiber assemblies.
ST connectors refer to having a "straight tip", as the sides of the ceramic (which has a lower temperature coefficient of expansion than metal) tip are parallel -- as opposed to the predecessor bi-conic connector which aligned as two nesting ice cream cones would. Also has a mnemonic of "Set and Twist", referring to how it is inserted the cable is pushed into the receiver, and the outer barrel is twisted to lock it into place.
ST connectors have a key which prevents rotation of the ceramic ferrule, and a bayonet lock similar to a BNC shell. ST connectors were predominant in the late 80s and early 90s. SC and LC connectors have risen in popularity.
For use with Singlemode or Multimode fiber optic connectors
Fits
Dynacom 6 Port ST Fiber Panel Fiber panel compatible with Dynacom and Hellermann Tyton brand fiber enclosures only