Abstract: The invention relates to a protective helmet with an outer shell (1) for distributing impact forces, an interior layer (2) accommodated by the outer shell (1) for attenuating impact forces, and a slot (3) for accommodating an electrical device (4), wherein the outer shell (1) has a chin shell area (6) to cover a chin portion of a protective helmet wearer, wherein the outer shell (1) forms a viewing port (8) for the protective helmet wearer to look through. The protective helmet is characterized in that the slot (3) is arranged on the chin shell area (6) in such a way that the accommodated electrical device (4) is arranged between the chin shell area (6) and the interior layer (2), wherein the protective helmet has an interior cover (10) for essentially completely covering the accommodated electrical device (4) in the direction of the viewing port (8).

Abstract: The production of polymers containing terminal halogen groups from cationically polymerizable monomers using a metal halide boiling below 50.degree. C. at normal pressure as catalyst and an organic halide corresponding to the following general formula ##STR1## in which X is halogen,n is an integer of 1, 2, 3 or 4,R.sub.1 and R.sub.2 represent C.sub.5 -C.sub.10 cycloalkyl or linear or branched C.sub.1 -C.sub.20 alkyl andR.sub.3 represents C.sub.5 -C.sub.10 cycloalkyl, linear or branched C.sub.1 -C.sub.20 alkyl, C.sub.5 -C.sub.10 cycloalkylene, linear or branched C.sub.1 -C.sub.20 alkylene or aryl, and the organic halide (inifer) contains from 5 to 50 carbon atoms and is present in concentrations of from 10.sup.-1 to 10.sup.-6 moles per mole monomer while the metal halide is added in a 1.1 to 100-fold molar excess, based on halogen atoms of the organic halide, at temperatures of from +10.degree. to -130.degree. C.