Binding and sealing strip

Claim 1

A lockable and unreleasable binding and sealing strip, comprising a flexible cord; a latch member at one end of and integral with said cord, said latch member having a head part having side faces in the shape of an arrowhead and having a pair of triangular notches forming acute-angled corners with said side faces; a locking frame at the other end of and integral with said cord, said frame being essentially tubular and having a pair of opposing side walls and a mouth for reception of said head part with minimal clearance, each of said side walls having a U-shaped slot therein forming an element the exterior of which is normally essentially coplanar with said wall and having a flexible root biasing said element inwardly of said mouth, said element being shaped in section perpendicular to said side wall for lodging in one of said notches and being disposed relative to said mouth so that said element is initially displaced outwardly of said side wall by rotation around said root on insertion of said latch member into said mouth and is moved inwardly by said biasing root into engagement with said notch as said head part passes said element, said notch of said arrowhead lying within said essentially tubular frame when engaged with said element for preventing disengagement of said element from said notch, said notch being so shaped that attempt to retract said latch member from said frame produces no outward force against said element, whereby said latch member is locked unreleasably into said frame by lodgement of said element in said notch.