US Patent 6978522 Clasp device for sheet materials

A clasp device for attaching to a sheet material includes a male member having a piercing member for piercing through the sheet material, and a female member having a bore to receive the piercing member of the male member, and to secure the male member and the female member to the sheet material, and to prevent the male member and the female member from being disengaged from the sheet material. The piercing member of the male member and the female member include engaging elements engageable with each other, to solidly secure the male member and the female member together.