This Knife Is the Best $8 You’ll Spend Before Prime Day Ends Tonight.

Posted on October 8, 2025 by resourcefulman

Amazon’s Big Deal Days promotion ends tonight, October 8, and before it ends, Lifehacker will share the best sales based on product reviews, comparisons, and price tracking tools.

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Like many Americans, I lament the fact that online shopping hurts local businesses, which can’t compete with convenient and inefficient perks like “free” two-day Prime shipping . Like many Americans, I still buy a ton of stuff online because it’s easier to avoid lugging home a giant wad of toilet paper from Aldi (at least as a New Yorker, I can still be skeptical about walking to the grocery store). But that also means that during Amazon Prime Day sales or the holidays, I have to deal with a ton of cardboard boxes.

Every year, the United States produces about 35 million tons of “containerboard,” the cardboard used to make shipping containers like Amazon boxes. I estimate that at least 10% of this material ends up in my home. Although I diligently recycle all of this cardboard (the American Forest and Paper Association estimates the “effective recycling rate” for cardboard at 85% —yay!), disassembling those boxes to place them in a recycling bin is no easy task.

A stationery knife made by a former Japanese sword company.

This $8 knife—yes, it’s sold on Amazon, though mine arrived in a padded envelope rather than a box—is made in Japan by Hasegawa Cutlery , a company that got its start nearly 100 years ago polishing and sharpening swords (the “Cutlery” part was added to the name after World War II, when the company first began making scissors ). Hasegawa’s marketing language implies that the company uses all of its Japanese swordmaking expertise to create consumer products, and while I’ve never tried to smash a stack of shipping boxes with a katana, I can’t imagine it would be much easier than using my Canary.

My previous methods for cutting cardboard—kitchen scissors or a steak knife (don’t be like me, kids!)—were ineffective, and box cutters, while certainly better, aren’t very good either. Cardboard is tough and fibrous, so a razor blade can cut through it fairly easily, but making a controlled cut is difficult because the blade will veer off-course if you try to cut against the grain, so to speak. Box cutters also dull quickly, but they’re still sharp enough to cut you if mishandled.

On the other hand, the Canary’s serrated edges, running all the way around, cut through cardboard like butter, whether you’re moving with or against the grain, pushing or pulling the blade, or using a sawing motion; its blade stays sharp much longer, making it much harder to cut yourself. (These qualities have made the Canary a favorite among cardboard crafters.)

What do you think at the moment?

I’m not much of a craftsman, but I’ve used my Canary knife on boxes, both small and large. In about a minute, I cut through the large box my new air fryer came in, leaving a neat stack of small cardboard pieces that are easy to throw in the trash. The knife works equally well on lightweight cardboard boxes, like those sold by Amazon, as it does on thicker ones, like the ones that held my Target furniture when unfolded.

Calling this little blade a life-changer might be a stretch, but it’s definitely saved me a ton of time—way more than the $8.

Looking for something different? Retailers like Walmart and Best Buy are running Prime Day sales, which are especially helpful if you don’t have an Amazon Prime subscription.

Walmart’s Prime Day sale runs from 7:00 PM ET on October 6th through October 12th and includes discounts of up to 50%. This is an especially great deal for those with a Walmart+ subscription.
Best Buy’s Prime Day sale runs from September 27th to October 12th and is one of the best tech sales in the world. It’s especially great for My Best Buy Plus or Total members.
Target’s Prime Day sale runs from October 5th to 11th, with discounts up to 50%. Joining Circle is free.