This Lock is a replacement to fit the full Fortress Hitch Lock range listed below. The Fortress Range can be identified by the Lock pin Housing welded on the top of the hitchlock and by the cross/cruciform shape key that inserts into the hitchlock housing. SAS Fortress Hitch Lock SAS Fortress A Hitch Lock SAS Fortress B Hitch Lock SAS Fortress BO Hitch Lock (discontinued) SAS Fortress IB Hitch Lock SAS Fortress K Hitch Lock If you need clarification of the lock you require, please send us a photo of your clamp and current lock (if you have it), and we will advise further.