An expansible plug comprises a closed shank section formed as a shank sleeve provided with a screw channel and a longitudinal divided expansible shank, the shank being formed by two shank halves provided with staggered expansible elements which interlock to form a closed expansion region, the expansible...http://www.google.fr/patents/US5431516?utm_source=gb-gplus-shareBrevet US5431516 - Expansible plug
