I used PPF on my Bauer Machs for a game last night. They slid like butter! I only added PPF to the knee blocks. How many games do you get in before the PPF needs to be replaced. I had a few areas peel back or crack....
if you are good at applying, it's permanent. I have never needed to replace it. I have had it since August. Anywhere possible, wrap the edges around the knee block so there is no edge around the friction area. Also, use a high dryer after it's on and rub the whole thing with a credit card.
