HALOs also have two sizes: Pre-2004 products use the small sleeve.

Fear not if your necks have been sanded: In general, a sanded VL 2000 hopper uses a Ricochet sleeve; a sanded eVLution II uses a VL 2000, and a sanded HALO uses and eVLution II sleeve.

These are sleeves required for your feedneck system to work. Additional sleeves can be used with a single marker and Twist-Lock Feedneck.