Hole Saw 4-inch Dia Hole Cutting Drill Bit for Drilling Holes in Wood, Plastic, Drywall, Thin Metal

My girlfriend and I decided to take on a full bathroom remodel. I'm a simple weekend-warrior, youtube mechanic/dyi'er so no professional experience going into this project. We installed an exhaust fan in the bathroom that required ventilation to the exterior of the home.I was nervous to drill a 4" inch hole through the side of my house as per the exhaust fan duct requirements but this attachment, with how nicely sharp the teeth were, didn't give me too much time to hesitate after I started drilling as it went completely through my cedar shingle and 2 pieces of plywood exterior within about 15-25 seconds. I was really impressed with how sharp it was and how perfectly clean the cut was. I gawked at how much similar hole cutters were at the big box stores and took my chances on this one and would easily take that chance again.

Cuts drywall nicely but had to remove the spring or the drywall circle will fall into the wall.

I had to do a little rework to the 4, small holes in the center. They pressed the center hole and then threaded it. The 4 holes around the center threaded hole rolled up on the press bend radius. They could have fixed this problem in a few seconds, but their arbor worked. I wanted to use my good arbor, so I am happy now this was a strange size and hard to find so I'm good with it now. I did the shiny stuff with a little cutter...

I got this because I needed a 75mm hole saw to drill a hole to mount a small fan. I was drilling though hardwood. The bit did a great job and produced a clean hole with minimal splintering.

Needed to make speaker holes for some 6.5s in my boat worked great went through the fiberglass and wood the template for the speakers asked for 147mm this was spot on

Used on drywall, works as advertised, would buy again.

Reviewing the Rannb 90mm/3.5inch hole saw.----------------------------------PLUS: Diameter is very accurate. This hole saw comes with a shank that fits my 1/4 inch drill.----------------------------------MINUS: Not very sharp out of the box, and gets duller quite quickly. Cutting through 3/4 inch baltic birch plywood, the saw started "grabbing" about 1/4 inch into the first cut. Reducing the downward pressure to a minimum helped, but it still took about 2 minutes to cut the first hole. Second hole took longer, and by the time we were at hole #7 it took about 5 minutes to cut through. By then the blade was so dull that it was basically grinding through the wood (as opposed to cutting). The sawdust was very fine, about what you would expect from #220 grit sandpaper. Also, what looks like anodized coating on the bit turns out to be paint, which burns off from friction (with attendant pleasant burned-paint smell).----------------------------------OVERALL: A cheap bit that worked for the intended purpose of cutting 7 holes, with probably 3 or 4 holes left before the bit goes into the trash. If you need a bit for a small number of holes, and are willing to drill very slowly, this would be a reasonable choice given the price tag.

I needed a 61mm hole, this hole saw worked fine in hardwood.No clue how long it will hold up with use.