Sizes, dimensions, material, for following open and enclosed drive ratchet braces: long head (box), short head, extra short head (pin brace), short head heavy duty (boiler brace), bit stock. Dimensions of drilling pillars for use with braces. For use with drills having Morse taper or square taper shanks, when necessary employing an adaptor, conversion details of which are included.Cross References:BS 51BS 328BS 427BS 970