Makes assembling and installing your trigger group much easier....if you have a large hole trigger / sear set....the sleeve allows you to assemble the sear spring and sear as an assembly so it can be dropped into receiver as an assembly ....eliminating the need for a slave pin..... to be used....AK European Fire Control Set (large hole) , Trigger,sear ,hammer sets ........these are the Sleeve & Spacer sets that are used with the "large hole" fire control sets ...New surplus ......3 pack.. includes 3 sleeves and 3 spacers...fits standard size trigger/sear axis pin....