Hi-lok collars are used in conjunction with hi-lok head pins to form a secure joint through the use of a the 2 threaded pieces. Designed for specific applications the new threaded hi-lok systems are easier to install and maintain with less special tooling needed. Monroe Aerospace is a stocking distributor of Aerospace and Mil-Spec hardware. We have an extensive inventory of hi-lok fasteners. Every part that we sell is in Factory new (FN) condition and we provide our company’s certificate of conformance for all parts on every order. See below for our products.