ALLEX Insulation Knife with Sheath Japanese Stainless Steel 8 Inch Long Cut, Insulation and Styrofoam Cutter with Blade Case, Serrated Sharp Duct Knife Tool, Made in Japan

Works really well for cutting fiberglass insulation

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Excellent knife, I've used it for an array of installation material, mostly for free handing around pipes or corners. It's extremely sharp so it's best to hold onto the sheeth. I've mostly used it on Fire protected batt and cuts happily all day. Would absolutely buy another, without a doubt.

I had previously tried several other knives & saws for cutting insulation with little success. This knife was a game changer and went through mineral wool insulation like a hot knife through butter. It's actually turned insulating the loft into a relatively easy job.

I use this to cut off spray foam in areas where my reciprocal blade couldn't reach. The blade itself is very flexible and allows you to cut with precision. The project of over, however the blade is still sharp, getting a lot of beating