These drip tips are hand made right here in Central Illinois with precision craftsmanship. The tips are made from the highest quality borosilicate (pyrex) glass, and are engineered to fit most 510 devices perfectly. They are easy to remove but willl not wiggle free while using your device. These drip tips will vary slightly in size and length due to the fact that they are completely handmade. They have been tested on multiple devices to make sure they perform as expected.