The L-099 and the L-100 series are the same rated couplers, the difference is the length through the bore, in other words the total over all length. They can work on engines up to 23HP@3600RPM. The size parameters are:
- outside diameter 2.5400"
- length through the bore L-099 = 1.06"
- length through bore L-100 = 1.38"
- hub material - sintered iron