a pilfer - proof plastic cap for sealing containers . the cap comprises a cap body , a band member and an annular wall extending upwardly and radially inward from the band member . a plurality of stopper tabs formed in the annular wall is engagable with the threads of a threadably capped container . the stopper tabs have a saw - tooth shape including a mildly inclined leading surface for smooth engagement of the cap with the container threads . the band member is connected to the cap with breakable ridges to indicate tampering . the band itself contains a breakable ridge to ease removal of the band from the container .