Precision Brand 20910 is made of Type 309, soft annealed stainless steel. Helps protect from scale and oxide buildup during heat treatment in atmospheric furnaces. Eliminates decarburization buildup. Resistant to chromium carbide precipitation during exposure to high temperatures. It can be used in furnaces up to 2240 degrees F. Tool Wrap protects the surface of air-hardening tool steels. This cut-to-fit foil creates an airtight envelope around your part. It can be cut, folded, and crease-sealed with ease. It will not tear easily in normal use. Realize the benefits of a vacuum furnace at a fraction of the cost. It is packaged in a convenient, re-closable carton.