This Metro 18" chrome plated wall mount shelf support comes with mounting plate with 2 shelf collar caps. Use single with supports (1WD) at each end and double supports (2WD) in between shelves in a run. Add 2‐1/4" to overall length of shelf for the mounting plates total. Can accommodate Super Erecta wire and solid shelves, Super Erecta Pro, MetroMax Q, and MetroMax i shelves.