This kit includes both the (40008) Windshield Repair Kit and the (52030) Diamond Windshield Burr. Most stone chips and small breaks only penetrate the outer layer of the windshield. This kit repairs them with a unique resin that actually penetrates the inner layer. Not for use on radiating cracks. The diamond burr with 1/8in. shank is used to make a precise hole in the glass so the resin can be more readily injected.