This is a clear glass vial, perfect for use as a slide on guitars, cigar box guitars, diddley bows and more! See below for the size specs of this vial - some adjustment with tape or other inserts might me necessary to get it to fit snugly on your finger. We dont know of any cheaper alternative for trying out a glass slide for your playing - sure you can try to cut or snap the neck off a wine bottle, but take my word for it - that takes some doing to get right, and there is some danger to it as well. Please be aware that this is standard glass, with about a 1/8" wall thickness. If you drop it, it will break... if you slam it into your guitar with excessive force, it will break. It is not safety glass. So use it with care and respect. We include a square of self-adhesive faux moleskin with every slide, so you can size the slides interior to better fit your finger as needed. Size Specs: Outside Diameter: 1"; Inside Diameter: ~3/4"; Length: 2 1/4"; Wall Thickness: ~1/8"