Locking device and the use of such device

A locking device comprising at least two relative each other turnable parts, a first part and a second part, comprising cylindrical axial extending holes, each part in circumferential direction being provided with at least one internal axial segment comprising at least one thread (3', 3") and at least one internal axial segment having a substantially flat surface (4', 4"), wherein the at least two parts (1,2;11,21) are limited turnable in relation to each other, whereby in a first relative end position for each of the two turnable parts (1,2;11,21) the at least one thread of the first part (3') and the at least one thread of the second part (3") are located straight above each other and the segments with substantially flat surfaces (4', 4") are located straight above each other and in a second relative end position for each of the two turnable parts the at least one thread of the first part (3') and the at least one thread of the second part (3") together form an all around thread (3), and wherein said relative turnable parts (1,2) comprise cooperating limitation means (7', 7"), limiting the relative turning of the two parts.