Draper expert 250mm plumb site dual view boat spirit level with magnetic base draper expert 69550 b i expert quality i b with front viewing plumb site 174 dual view 153 vial cast aluminium with one horizontal one 45 176 and a plumb site 174 dual view 153 vial special milled base with two ceramic magnets accuracy 0 5mm per 1m 0 029 176 in standard position manufactured for draper tools by kapro display packed draper expert 69550 250mm plumb site dual view boat spiri