The Silica Sound 426 bottleneck slide is is handblown and has a thickened end to promote a unique grip on the tip of your finger, while providing added mass for better sustain.  Each one has a colorful, artistic design (sorry, no choice). The wall is 4.0mm thick, with an outer diameter of 30.0mm, and an inner diameter of 22.0mm. The length is 2.6". No two slides look exactly the same and the taper varies on each slide, some thicker, others thinner.