The Adjustable Receiver Link is designed to maintain and secure the opened position of your AR-15 upper and lower assembly. The upper link utilizes an integral pin to engage the upper receiver. The short lower link provides an opened position of 1.2"-1.5" from pin to pin, enough room to insert a bore guide. The longer threaded link will provide an opening of 1.4"-1.8" from pin to pin. All three components are constructed of corrosion resistant plated steel. The kit comes with one upper link and two threaded lower links (one short, one long) to provide a total adjustment of approximately 3/4".