Base Lab Tools flexure grip post holder is 1.5 in. long and designed to hold 1/2 in. optical posts. The flexure grip design outperforms common screw against post designs. Each post holder has a 1/4-20 mounting hole in the bottom and a thumbscrew drive for hand tightening. In tight spaces, the thumbscrew can be replaced with an #8-32 cap screw. The unibody construction of these flexure post holders provides superior performance over multi-part post holders.