These are classic Shaker style cabinet knobs, made from solid oak. 
The wood is untreated and ready to be stained, waxed, oiled or varnished.
The grain may vary from that shown in the photo.

Product details:
Installation: screw ( not supplied) 4 x 40 or 4 x 45 standard wood screws work well depending on thickness of door or drawer
Diameter: 29mm
Depth: 29mm
Finish: Unfinished - ready to be painted, waxed or stained.