SUB-420: Aluminum Forend with space for up to FOUR Picatinny rails. This replaces your old SUB2000 forend with a high-quality, durable bi or quad rail. Recommended for the 1st gen Sub 2000 only. This kit is available as full mounting kit with all Four (4) Rails. 2nd gen sub 2000: With this accessory installed, you will not be able to lock the firearm in the folded position. Will not fit on the 3rd gen.