away portion 135 39 of the first embodiment of fig8 in addition material 138 is provided at the free end portion 100 39 to reduce the sliding coefficient of friction between the free end portion 100 39 and the tape t the difference between the first and second embodiments is that in the second embodiment at least one cut out portion 152 is provided in the resiliently flexible element 100 between the free end portion 100 39 and the fixed end portion 100 34 as shown in fig1 a cut out portion 152 is provided along the lower edge and a cut out portion 152 39 is provided along the upper edge of the resiliently flexible element 100 the cut out portion 152 152 39 allow the amount of tension on tape t 39 required to move the resiliently flexible element 100 between the normal braking position and the automatic release position to be changed or preselected the second embodiment of the holder 110 is shown in fig1 16 because the configuration of holder 112 is an identical mirror image of holder 110 only holder 110 is described holder 110 of fig1 16 is formed from a block 160 provided with an arcuate gap defined by wall surfaces 162 and 164 the gap between wall surfaces 162 and 164 is greater than the thickness of the resiliently flexible element 100 that is slidably disposed therebetween as shown in fig1 the gap defined by wall surfaces 162 and 164 is opened at the top and at one end and is closed at the other end by an end wall 162 a tang 132 is provided on the inside bottom surface of the gap.