These blocks are machined from solid white polyethylene providing the reloader with a very durable, easy to clean loading block. Each block is machined to fit the specific cases you reload and has finger grooves machined into the sides to provide a sure grip. Each hole has a slight chamfer for easy case head entry. The ""Poly"" blocks are dishwasher safe for easy cleaning. The white material was selected because spilled powder easily shows up. These blocks were designed for competition shooters that shoot from the bench. Each block has 25 holes and an open tray for throwing the empties into. When you have to hurry during a wind condition there isn't enough time to Mfg: Sinclair International