These Slot Mount Standoffs are designed to be mounted either vertically or horizontally, and can be used for installing shelves without drilling holes in the material. The nylon tip set screws hold panels firmly in place without damaging panel material or glass. This 1-1/4"" (31.8 mm) diameter Slot Mount Standoff is available to hold 1/4 (6 mm) thick material. Maximum recommended shelf projection from the wall is 5"" (127 mm) when Standoff is anchored to the wall stud.