Slip these Renishaw styli into undercuts and grooves that are too narrow for other styli. When the side of the disc touches your workpiece, these styli trigger your coordinate measuring machine (CMM) probe to send a signal and measure geometric features. The disc is completely round, just like a ball stylus, so these styli contact your workpiece with the same precision. However, they can’t measure in as many directions as ball styli. When space is tight, they’re a great alternative to star styli for inspecting features inside holes. They work with both touch-trigger and scanning probes.