The materials discussed above for elements 22, 24, 58 and 60 of clamp systems 20 and 50 will be suitable, and especially preferred will be a rubber or thermoplastic elastomeric material such as the material sold under the tradename of DYNAFLEX D-series (styrene-butadiene elastomer sold by GLS Co.) or the material sold under the name of DYNAFLEX Gseries (styrene-ethylene/butylene-styrene copolymer