My grip size is 12cm 4 6/8 and I have a racket 4 3/8 with overgrip i.e. 4 4/8. It is not fit enough and getting some pain with it. I want to increase its size by 1/8 inches but which kind of Heat-shrink sleeve should I use? Can I buy it from any warehouse store or does it need to be tennis-specific? What kind of features are required from the heat-shrink sleeve?
P.s. the picture is a little bit misleading but when I press the ruler to my hand: the distance from the top of my ring finger to the second crease is 12cm.