T bolts with washers and Knobs for your hold down slots. Work on CNC routers and router tables wherever you have t-slot installed. Knobs make it much easier to tighten up your work piece. Bolts are 8mm x 80mm long (3inches) , washers are 8mm and Knobs are 8mm T bolt head is 26 x 18 x 2 m. included is a bundle of wooden hold downs for CNC ,or other machines using T track