The 12410 Concave Series of tips are designed to work with the Brunson Invar System. On one end, a 3/8"-24 external thread mates to our standard Invar system tubing. The other end provides a concave mount that is made to fit on a 1/2" tooling ball, while holding the effective length to a precisely known standard (see drawing and table below). The concave tips allow you to take measurements from tooling ball fiducials permanently mounted on fixtures, and perform "leapfrogging" measurements using a tooling ball placed temporarily between points of measurement or alignment interest.