IRWIN Tools MARATHON Vinyl Siding Circular Saw Blade, 7 1/4-inch, 120T (21830ZR)

I used this blade with a corded SKIL 5280 7-1/4-Inch Circular Saw to cut backer board for a shower reno in my house. I cut mostly half inch and a few sheets of quarter inch Durock, total of about 12 sheets, but including a bunch of small pieces for a shower niche and a bench.I was on the fence about buying this because it's expensive (almost as much as the saw!) and because I had previously been able to do an adequate (but slow and painful) job cutting Durock using a razor knife (and a whole bunch of blades) on another job around the house. But I was looking for something that was (a) faster, (b) cut a cleaner edge and (c) didn't wear me out so much to use - so I took the leap.I'd say this blade fit all 3 counts.(a) It literally chews through Durock. Occasionally it'd hit a hard spot and would take a second to catch, but by and large the Durock was toast. It was really fast, it probably cut through a full 5' in maybe 10-15 seconds. This is several times faster than I can go with a razor knife (scoring, then cracking, then cutting again ...) - especially as those razor knife blades get dulled up after seems like just a couple cuts.(b) The edges were really clean. I clamped a guide board along the Durock to keep the saw straight, and it had absolutely no problem keeping straight. No waving edges to have to go back later and clean up in place. If you were really in a hurry, you could probably use it freehand, since it didn't struggle at all cutting the material. Overall those really clean edges made fitting them together much easier and greatly reduced the amount of time I had to spend scraping little protuberances to make all the sheets fit together.(c) I'm 39 - which I consider not real old, but also not real young, and anything I can do at this point to save my arm and shoulder some stress is welcome. This thing just took a lot of the effort out of the job. Hand cutting, especially with a dulled up razor, is something I'm happy to minimize. It just made it much less taxing of a job.The one blade lasted the entire job and I couldn't tell any difference in cutting from beginning to end. I'm assuming I'll be able to use it on my next project.There were a couple downsides:- It did make a lot of dust and blew bits of board off at high speed, and it was loud as all get-out. As others have said - wearing a mask, goggles and ear protection is a must. I did all the cutting outside the garage, I'm not sure I'd use it indoors unless it was really well ventilated.- It's expensiveOverall, I would definitely buy again despite my angst at the price point.

i am a big Dewalt fan. thier set was twice the money, if someone is doing a lot of dados, the Dewalt is a great choice, but for doing a few now and then, this does the trick. i did try others at this price level, and this set was cleaner.

I used these to cut baseboard and door casing. Once I moved to the laminate flooring the blade burned thru the cuts Smoking! Won't last long on anything dense. It's a cheap blade good for less than 1000 sq ft trim. That's all I needed!

I bought it to cut plexiglass and it sure did the job.

Works great in table saw for concrete lap siding, doesn't get hot like smaller blades do.Ripped around 40 linear feet of siding and the blade seems to have plenty of life left.Packaging a little odd; there were clearly stickers on the packaging that had been removed. I assume old stock or inventory-buy-out. Great value.

It cuts

This blade is cheap. Extremely cheap. I was able to cut through about 8 feet of MDF before it became dull and started smoking. For a really small DIY project, it'll do great. For anything that requires more than a handful of cuts, don't bother.

This product is exactly what they say it is