The new RIDGID bi-metal hole saws have just become more cost-effective while offering maximum cutting performance.They are now made with a cutting edge of premium M42 HS steel and feature a patent-pending tooth set design with twice the life of the old hole saws.External tests prove that the RIDGID bi-metal hole saws cut faster than comparable hole saws from the biggest 5 competitors, by:39% in 16G 304 stainless10% in 1/2" OSB wood12% in 1/4" mild steel plateLeadwright, electrician, general kits each contain a selection of RIDGID hole saws and hole saw holders for cutting through wood, plastic, machinable metals, stainless steel alloys, cutting wood with nails.