If you use a rubber washer it is considered part of the thickness. Most people purchase to short of movement. The size is not the size of threaded part. If anything order a little larger than you need
Accepts Sweep Second Hand
2 3/16"w x 2 3/16"h x 5/8"d
5/16" Threaded shaft diameter
Complete with 1 set of hands, brass washer, hex nut, and open nut to use with second hand included in price including sweep second hand. If you do not want a second hand, let us know and we will send a closed nut
These have a steady movement of the second hand and do not have the very slick ticking movement that the standard quarts ones have. The standard movement has what they call a step on the second hand moving. Otherwise they are both equal in accuracy. I have not had problems with either one of them.