Adjustable, releasable binding fastener

A fastening device has male and female portions, the male portion having a base and a downwardly extending post with two vertical series of horizontal ratchet teeth, one on each side of the post, and two convex lobes extending outwardly in diametrically opposing positions between the two vertical series of ratchet teeth. The female portion has a base and an upwardly extending collar consisting of two curved halves. Each collar half has a series of horizontal ratchet teeth on its inner surface. The circular space defined by the collar halves continues through an aperture in the base. The ratchet teeth may also continue on the inside wall of the aperture. To assemble the fastener the collar of the female portion is placed into a binding hole in a stack of paper, and the post of the male portion is placed into the opposite side of the binding hole, with its base mutually aligned with the base of the female portion. The post is pushed manually into the collar, where its teeth lock with the teeth in the collar. To disassemble the fastener, the opposing bases are rotated until the teeth disengage, and the portions can be withdrawn from each other and removed from the stack.