Threaded insert: No. The knob does not appear to have a threaded metal insert. It is designed to be attached with the supplied 8-32 × 1" machine screw through the cabinet door and into the knob. Belwith specifies a pilot hole for the supplied screw. Wood species: Birch. The P685-UW is part of Belwith's Natural Woodcraft collection, and catalog information specifically identifies the P685 as birch. Size: 1-1/4" diameter, 1-1/8" projection, with a 1" base.