key surface 12 and a pivot 13 at the other end with at least one corresponding key surface 14 as well as locking stops 15 the outer pipe section 3 furthermore has an inner collar 16 with two longitudinal slits opposing one another which cross section corresponds to the outline of the carrier stops 19 at the rearward end of a pipe type inner section 4 and u2014 like shown in fig4 u2014 are situated rotated by 90 u00b0 with respect to the carrier stops in proximity to the inner collar 16 is a inner surface grove 20 of the outer pipe sections 3 into which the carrier stops 19 mesh in the coupled state of the two pipe sections 3 4 furthermore the front end of the outer pipe section 3 has an inner collar 21 which similar to the inner collar 16 has two opposing longitudinal slits 17 18 fig4 the rearward end of the inner pipe section 4 is provided with a receiver 22 for the carrier stops 15 at the front end of the neighbouring inner pipe section 4 in a coupled state these carrier stops 15 are situated behind a band 23 at the rearward end of the inner pipe sections 4 shown left in fig3.