This is a VRP Piston Caddy. It is a small plastic case with an insert that will fit 4 sets of pistons. Both 8th scale and 10th scale pistons will fit in it. The inner assembly is removeable so you can take it out of the box and get the pistons off easy. We include 4 small oil resistant o-rings to hold each row on, and the case has a latch so it won’t come open in your pit box! No more pistons laying around!! Organize them! And keep them nice and nick free!