CRL Glass Shelf Rests are designed to attach through glass, wood, or metal walls. The Shelf Rest supports the glass shelf with very little metal showing in comparison to typical standards and brackets. The substrate must be drilled with 1/4" (6 mm) diameter holes in order to accept the threaded barrel of the Shelf Rest. The 1/4"-20 threaded rod may be replaced with a Hanger Bolt for attaching directly into a wood stud. Size: 3/4" (19 mm) long x 9/16" (14.3 mm) diameter.