Union Central Gearboxes Union Aluminium Door Gearbox Type 2 £54.50 Ex VAT£65.40 Inc VAT Qty: larger image larger image This Union gearbox type 2 is fitted mainly to aluminium doors. View photos for dimensions. Aluminium Door Lock Specification: Key to spindle: 48mm Backset: 31mm Turn key once to throw deadbolt Click here to view compatible Lever/Lever door Handles. Please check that these handles cover any existing screw holes in the door. Model: DU-DBUN2 Manufactured by: Union