This unique design is the original multi-bore carb cap, the six individual air paths create a unique dabbing experience, as the six holes help to stabilize the temperature and spread out the material for a more consistent dab. Each cap is made by skilled, US-based craftsmen using 100% premium borosilicate glass. The cap is designed to work with any American-made, 25mm nail. (We’ve found that you can use a 30mm nail, but we’ve had best results using 25mm nails with this particular cap.)