B........One Piece Back
H........P=Pegboard H=Hardboard
NW........Nominal Width 3' or 4' (91.44 cm or 121.92 cm)
NH........Nominal Extension Back/Extension Upright Height ........36" to 72" in 6" Increments ........(91.44 cm to 182.88 cm in 15.24 Increments)