Bathroom dead bolt, suitable for bolt through bathroom thumb turns to take a 5mm spindle.
Available in 2.5 inch - 64mm (with a 45mm backset), 3 inch - 76mm (with a 57mm backset), 4 inch - 102mm (with a 82mm backset), 5 inch - 127mm (with a 108mm backset) and 6 inch - 152mm (with a 127mm backset) sizes, with polished brass, bronze/antique brass, black, polished chrome or satin chrome forend and strike plate.