In a resin molded controlled-release product which comprises a volatile or elutable active agent dispersed in a substantially transparent and inert resin molded material, the improvement which comprises a colored material located inside or on the back surface of the molded product which is not visible...http://www.google.es/patents/US4279213?utm_source=gb-gplus-sharePatente US4279213 - Resin molded productions designed to display extinction of activity
Resin molded productions designed to display extinction of activity
