Chains models
SPT/CAL
Calibrated triple spike
SPT/Q/CAL
Square Calibrated triple spike
SPT/OP
Oval triple spike ( less hammered than SPT/OM)
SPT/OM
Oval triple spike ( more hammered than SPT/OP)
SPT/P
Oval triple spike hammered Flat
SPT/MT
Half-round triple spike
SPT/T
Round triple spike