Jack knives originally had squared-off bolsters. The sleeveboard pattern, which takes its name from an ironing board attachment for shirt sleeves, rounds both ends and tapers from one end to the other.
Historically, sleeveboards have featured many different blades, usually hinged on the larger end of the frame.
Great Eastern Cutlery, with its passion for traditional knives, makes a number of variations on the sleeveboard pattern. This one, the popular #15, measures 3.5" closed.