Listing is for 1 piece of Techniks part # 22403, CAT40 1/2" capacity self tightening keyless drill chuck with 4" gage length supplied with spanner wrench. Techniks drill chucks have 3 times the holding power of most traditional drill chucks. This tool his handy for holding non-standard shanks without fussing around with a collet. The chuck is replaceable and is held in place by a drawbolt.