Product Overview
Model 726 is a modular version with a larger recess to accomodate 3/16" x 1/2" uprights (not included). The upright attachment holes have also been threaded to allow you to attach your uprights with screws. Extra springs, pins and an alignment tool are included.
(https://www.beckerorthopedic.com/Product/AnkleComponents/DoubleAction/726)