Review (3/5): *Not* credit card sized - won't fit card slots
Since the title of the listing expressly said these are credit card sized, I didn't check the dimensions. My own fault, I guess, but they're actually much larger than a credit card and won't fit in any of my card slots.
Other than that, they're cleanly cut from stainless steel, don't have any burrs to snag hair, I expect they'll work well if you have a place to carry them. If the listing hadn't specifically said "credit card" sized, I would give 5 stars.