Siser is a polyurethane(PU), ready-to-cut material designed for custom garment decoration. It is designed to be used with a cutter plotter and heat press. Why is Siser our number 1 selling cuttable heat transfer vinyl material? Simple, the Siser Advantage? Siser applies at a lower temperature, can be peeled HOT or COLD, It’s also extremly durable wash after wash uses a lower pressure setting for application. Siser is thinner than our competitior’s material and offer a one-step application that’s great for multiple layers.