4229 Ernie Ball Borosilicate Glass Electric Guitar Slide LARGE 69mm Long 30mm.   Ernie Ball’s glass slides are made from borosilicate glass for a durable, smooth gliding surface providing a clear, smooth tonal voice. Available in three sizes for your preference and playing style. 69mm long, 30mm outside diameter, 4mm thick.   Seamless Pyrex glass Silky bluesy slide sounds 4mm thick 30mm outside diameter 69mm long FAST & FREE SHIPPING!