How have i never seen these before? They're clip on strain reliefs, for when you forgot to put a boot on before terminating rj45. You can still put a strain relief boot...after the fact. Because who would forget? Not me of course. https://www.homedepot.com/p/NTW-net-Lock-Lockable-Cat5e-RJ45-Snap-On-Strain-Relief-Convertible-Boots-NL-SRNRT-CL5/302606275