Heavy duty carbon steel. Card of 5 blades. Fits any 4" wide blades scraper tool. Precision ground high carbon steel knife blades. Blade body has knock outs for securing in tool head American Line's Wide Scraper replacement blades are manufactured from quality high carbon knife steel. Each 4" blade has notches in the body for secure positive locking into the tool head. Each blade is precision ground on one edge to allow for storing the blade in the tool head with the unground edge up for safety. Precision grinding ensure the blade can be used on delicate surfaces like glass even though it is durable enough for scraping rough areas or removing heavy debris.