This is our XV4 Piston Pro Pack. It includes 2 sets of 5h1.5, 2 sets of 6H1.3, and a set of 8h1.2 and a set of 8h1.3 pistons, and hardware. All in a VRP Piston Caddy! The pistons come with the Transition Valves (not installed). The Rebound booster hole has been precision drilled to the exact size our testing found to be the best ‘all around’ setting. This yields excellent results that are proven on a variety of track surfaces. From rough, blown out tracks, to smooth, indoor clay, the VRP Piston makes a positive difference and gives you a Big Advantage over the competition! Simple to understand! The Pistons are designed to increase the Rebound only. They do not change the compression from what you would have running stock 8 hole 1.2 pistons. No crazy set up changes. No scratching your head if they work or even made a difference. Anyone who has run them will tell you it was better from the moment they squeezed the trigger! No questions! ….Amazing! You will feel a difference in the piston because it is designed for the oil to flow through the holes instead of around the perimeter. We suggest starting with the normal oil you would use. Remember, the compression stroke stays the same, only the rebound is quicker. Important: The VRP ‘XV4’ Pistons are designed to have a washer under and over them. It is important to run washers and that they are correctly installed. Each set of pistons is supplied with a Washer Hardware Pack to make sure you have what you need to install them. Each set of pistons comes with 4 different upper washers that are color coded. The washers are made to more or less cover the rubber valves to give different rebound rates. The Black washer gives the most rebound, Red is a little less rebound, Gold is slightly less rebound than the Red washer, and the Blue washer is the least rebound. For tracks that are loose and low grip, or very blown out with large ruts, more rebound is better. On smooth or tracks that have very high grip, less rebound is better. We suggest starting with the Black Washer in the rear pistons, and the Red Washer in the front pistons. 15.80mm Group (The "Universal" Fit):Tekno / Kyosho / SWORKz / Team Associated (AE) / Sparko / Mugen / Mayako / XRAY / Agama. 15.85mm Group (High-Pack/Tighter Fit):TLR (Team Losi Racing) / Hong Nor / JQ Racing / Serpent. 15.93mm Group (HB Fitment):HB Racing (Hot Bodies) / Infinity / WRC
