Who seriously needs knife cufflinks? I can think of a few guys, Tony Stark, Bruce Wayne or James Bond might find them handy. These stainless steel shirt decorations aren't just for looks, they're deadly enough to take your eyeballs out.
I'm not quite sure which pair of cufflinks I prefer more, the flash drive USB cufflinks or these. Both are snazzy and handsome, yet functional.
These knife cufflinks are seven eighths of an inch long and each blade is nine sixteenths of an inch with a little notch to open it up. I don't imagine you can get these through airport security, but at least it comes with a diamond dust sharpener!
If I even had a shirt with cufflink holes, I'd buy a pair. Unfortunately, I don't. If you like them, you can buy them at YouGneek for $55. Just be careful not to use them to hurt anybody.
Use them with responsibility as its product description suggests: for opening envelopes, cutting packing tape, and peeling oranges.