Abstract: A strong, resilient, thin-walled material in a tubular shape stretchably fits over a pre-existing golf club grip for enveloping and frictionally engaging the pre-existing grip. The tubular body has a butt end which, when installed, abuts a butt end of the golf club grip, and an opposite open end that overlaps a distal end of the pre-existing grip, distal from the butt end. Projecting outwardly from the tubular body are two ridges for assisting a golfer in the proper positioning of his or her thumbs, and a plurality of semicircular ridges for assisting a golfer in the proper positioning of his or her fingers. Preferably the tubular body is elastic and can be stretched, over a range, to a length that matches a desired hand size, and further includes a plurality of catches for holding a selected stretch of the tubular body. The catches can be inner ribs proximate a distal (from a butt end) end of the grip that can be individually caught by the distal end of the pre-existing grip.