Pb fastener soft touch black 16mm amp 19mm knobs for 6mm splined shafts pb fastener 3030407 this blackred soft touch knob 16mm from pb fastener amp components has been manufactured with a polypropylene and thermoplastic rubber matt material on the knob making it soft and very comfortable to handle the splined 6mm spindle socket guarantees a secure grip even on smooth spindles the combination of this particular knob features a black body with red pointer and cap pb fastener 302t