In 1999, Songhurst Guitars invented the first ergonomic slide which has been favored by professional acoustic and electric players ever since. The signature is our tapered interior design, which fits like a glove. Other features include the knuckle cutaway for finger flexibility and the dished finger rest for perfect control and vibrato. Polished brass offers the smoothness of chrome with the thick tone of brass. Medium Rock Slides® are a perfect weight for most styles, heavy enough for long sustain on acoustic guitars, but light enough to easily control for fast electric playing. Inside Diameter: 19.5mm Total Length: 57.5mm Weight: 70g USA Ring size: 8-10