Description Jim Dunlop pyrex glass slides are preferred for full, rich tones. They sound warmer and more resonant than metal slides, producing smooth transitions with minimal string noise. Pyrex Glass slides are the top choice for many acoustic players, and they are also favored by electric players who want the purest slide tones possible. Try the warm rich tones of the J213 HEAVY SLIDE: 23(inside) x 32mm x 69mm in length.  It fits a ring size 14. When playing slide guitar, the string is not pushed down on the fret. The slide lightly pushes the string directly over the desired guitar fret (as opposed to playing next to the fret with your finger). Which finger??- You first need to decide which finger will hold the slide. Choose from the 2nd, 3rd, or 4th finger. The decision will be based on two factors: which finger feels most comfortable and the need to use the other free fingers for fretting notes. 2nd finger muting- Most of the time the 2nd finger should lay flat behind the slide. This will provide muting of unwanted guitar strings.