This is the material fitted to all top-class shooting jackets. It's called 'Top Grip' and it looks like granulated rubber stuck to a cotton cloth.

It can be cut with scissors or a sharp knife and glued or sewn to the elbows of your shooting jacket (or anything else you fancy). It measures approximately 180mm square. It is available in larger sizes but only in multiples of the 180mm, e.g. 360mm x 540mm, etc