Abstract: An antitheft device for marking articles for sale and comprising two members, which automatically interlock one another when one member is inserted in a cavity in the other member, the first member being a rod-shaped body with a completely or partially pointed insertion end, whereby said rod-shaped body is capable of engaging for instance balls loosely arranged in the cavity of the second member, a third member of magnetizable material being inserted below the loosely arranged balls, whereby a resilient member with an upward driving force is placed below said third member. According to the invention the resilient member is an annular plastic member with inward connecting parts connected to a centrally arranged disk-shaped plastic member pressing against the third member in the cavity, the annular plastic member being secured by way of squeezing to an annular groove in the bottom of the housing.

Abstract: The lock is preferably to be used for burglar alarms for marking articles for sale, and it comprises two members automatically interengaging when the first member is inserted into a cavity in the second member, a loose third member being positioned in said cavity. The locking effect is provided by the loose third member comprising one, optionally more inclined surfaces capable of being tangent to and sliding along a corresponding inner wall in the cavity of the second member. The cavity of the second member is pointed upwards, i.e., towards the inlet opening. A spring is provided below the loose third member, and this spring presses as a consequence of the inclined wall the third member upwards and towards the first member.