Original castle nut Flanged castle nut with 1”-14 thread pitch for many rotary cutters from manufacturers. This nut fits 4', 5', 6'and 7' cut mowers with 40hp and 60 hp. gearboxes 
OEM 120050
OEM 11-008
Befco #503-441B
Brown Mfg #TC-134F
Ammbusher #11-008
Woods #1018331
Servis Rhino #00758692
Worksaver #650849
King Kutter #501110
Big Bee
Darrell Harp
Kodiak
WAC, Hawkline #11-008
Tebben #11-008
Howse