Oil drain plug / block-off plug. 1/4" NPT threaded. Shorter version of the OEM 765 crankcase / sump drain plug. The Feuling plug is just 0.265" tall vs. OEM 0.465". The further the bottom plug installs into the crankcase; the more of the scavenge cross port is blocked off. For optimum oil scavenging & lower sump levels; it is advisable to use the shorter sump plug which will ensure the cross sump port is wide open and allows the oil pump to pull as much as possible from the sump. Eliminate blocking the internal engine case scavenge pick up hole with the FEULING bottom case Short Sump Plug. A common issue with both Twin Cam and M8 engines (more common with Milwaukee Eights) is the sump plug can block off the internal scavenge (return) pick up port. By using a shorter plug; we eliminate the possibility of the plug blocking off this cross port.Note: The M8 main sump cross port on the inside of the M8 engine case is in a slightly different location & height in each engine case. This cross port is created when the bottom plug hole is machined and tapped by the factory. The machining breaks through the casting wall; creating the sump port. Whereas the Twin Cam engine cross scavenge pick up hole is a machined bore; and is in the same location in every engine case.