The 21mm irwin bi metal high speed hole saw is specifically sized for many plumbing and heating applications, particularly when installing radiator valves, small bore pipes and associated fittings. This precise diameter is frequently specified in installation guidelines, making it a must have for heating engineers and plumbers. Featuring robust bi metal construction with electron beam welded teeth, this 21mm holesaw maintains cutting efficiency through demanding daily use. The sharp, variable tooth design 4 6 pitch delivers faster cutting action with minimal effort, producing clean holes in materials from aluminium through to stainless steel. Features and benefits bull 21mm diameter ideal for radiator valves and pipework bull bi metal construction provides exceptional durability bull variable tooth pitch 4 6 ensures fast, clean cuts bull electron beam welded teeth offer superior strength bull cuts diverse materials including copper, iron and wood bull professional quality built for trade applications specifications size mm 21 material bi metal pitch variable