Go with Dunlop Pyrex Glass Slides for a warmer, thicker tone accentuating the middle harmonics of your sound. Dunlop slides are today"s most popular slide. Processed from high quality Boron Silicate. Heat treated and annealed to produce a flawless tube. The Dunlop 212 17mm x 35mm x 51mm, and fits ring size 6.5. For authentic slide tones, Dunlop"s your choice!