It sounds a lot like a skirt steak. They are somewhat long and about 2-3 inches wide. The name you refer to sounds like a reference to it's general size being similar to a leather strop used to sharpen knives.
It could also be a Flap steak. It’s often used as a substitute for skirt steak, and it’s much cheaper than skirt steak (almost half the price). Here is a link with a description: