kwb 6-piece multi-fluted hole saw Ø 46, 53, 60, 68, 74 and 81 mm with good cutting performance, long service life, heavy aluminium die-cast backing plate and hexagonal shank for universal use - Amazon.com
wolfcraft "Professional" Multi-Blade Hole Saw, Ø 25-62 mm I 2160000 I Saw with 7 Quick-Change Blades, Ø 25-62 mm, Cutting Depth 33 mm: Amazon.com: Tools & Home Improvement