The ledges measure 2.5" on the back, 2.5" base (usable space) and 1.5" front lip and are made of solid hardwood. The entire ledge depth is 4” from wall to front. Ledges mount through the back using pre-drilled holes and are simple to hang. Pre-drilled holes are 16" apart (which is standard with most stud distances). Screws for mounting into studs are included (recommended due to weight of hardwood). Mounting hardware is rated for 25lbs per set of two studs. This mounting hardware included is optional and you may choose to use your own (molly bolts, etc) The ledges are assembled with no nails and finished only with a simple all natural oil We use 100% natural, solid hardwoods; therefore, there may be some figure in the wood.