Shell Seating Post (post only) - 12, 20 & 28ga. Part # Size320200, Size320220, Size320228 Can be found on these parts lists: Price/Part List Key # 800Plus #120 900 (#1000-4931) #124 900 (#4932 & Above) #124 Plat2000, L/S-1000, 950 #124 800B, C & Cvt. #32-2 Note: If you are looking for a shell seating post for a 16ga, you need the 20ga. post