H.18D has the same specs as the H.18, except includes a duplex spring for added flexibility. H.18 is for use with only 2.35mm (3/32") shank burs. A press lever action is all that is required to change accessories. It features a very slim grip and pre-lubricated ball bearings that do not require any lubrication. 10-3/8" long, 19/32" dia.