Threaded GrinderMinders are our original 1″ spherical shape, but without the stem. Instead, we have placed a threaded hole up into the sphere for the purpose of bolting them in place from the underside of the surface you are protecting from skateboard abuse. Customers order the nuts and bolts separately, according the thickness of the surface. This design is ideal for bench slats, water features, and unusually shaped handrails that are accessible from the underside. Same great protection, but with the needed versatility for unique applications.