These are oscillating multi-tool saw blades, used as accessories for power tools to perform various cutting, scraping, or sanding tasks. The U-shaped top is a quick-release design, allowing for easy, adapter-free attachment to most mainstream multi-tools. They are primarily used for cutting different materials such as wood, plastic, soft metal, drywall, and nails, depending on the specific blade's material and teeth configuration. The universal open-back design allows compatibility with many major brands, including DeWalt, Makita, and Bosch, but generally not tools with the Starlock system unless an adapter is used. Grab yourself bargain and thanks for looking
eBay