WhWhile foam grips are great for many applications, some applications require tubing that will not slip through hands or gloves. Testrite has the ability to add a While foam grips are great for many applications, some applications require tubing that will not slip through hands or gloves. Testrite has the ability to add a knurl to the outside of our tubing to increase friction between the user and the tubing. As shown in this example, Testrite added two grip sections, showing the operator where to place each hand.rl to the outside of our tubing to increase friction between the user and the tubing. As shown in this example, Testrite added two grip sections, showing the operator where to place each hand.ile foam grips are great for many applications, some applications require tubing that will not slip through hands or gloves. Testrite has the ability to add a knurl to the outside of our tubing to increase friction between the user and the tubing. As shown in this example, Testrite added two grip sections, showing the operator where to place each hand.