Ref. :FBLS.01BC.26 / FBLS.01BC.27 / FBLS.01BC.41 / FBLS.01BC.42S / FBLS.01BC.43 / FBLS.01BC.44SThe FBLS.01. BC.41 is the patented model FBLS.01. BC.22 but with an improvement: the clasp can completely disengage in one direction. Disengagement in both sides may be undesirable in some assembly. The FBLS.01. BC.42S is the secure version of FBLS.01.BC.12.The FBLS.01. BC.42S is the version with the 8 security of FBLS.01.BC.21R.