a double-start modified stub ACME mating thread for improved protection against cross-mating and thread damage. Connector shells are machined aluminum or stainless steel, and are designed to accommodate (depending on insert arrangement) Glenair size #16, #20HD, or #23 fiber optic termini (termini sold separately. ) Metal clips inside the connector body lock the termini into place. Termini are removable. Fluorosilicone seals and rear grommet protect the connector from water ingress. Choose hex or.