The MK K8821ALM is an Aluminium, 1 Gang, 38mm deep back box, without knockouts around the side. It does, however, have a knockout in the base. It also has a self-levelling platform which helps ensure the mounting frame is always positioned correctly so it does not need to be adjusted. Self-leveling platforms ensure mounting frame is always positioned correctly without adjustment. Suitable for the MK Grid Plus range. The MK Metalclad Plus Range is made from heavy gauge steel making it a very tough set of products. This means they are ideal use in factories, workshops, garages and sheds. · · · No. of gangs 1-2 · · Mounting type Surface · · Fixing Centres 60.3mm