Theft protection during storage and transit. Does not need to be removed during use of the propeller. A free spinning collar will turn if attacked by gripping tools without loosening the lock. Constructed of naval brass and hardened stainless steel
options are
Mercury & Mariner over 70hp - nut thread 3/4" x 16 part number 74039
Mercruiser Alpha One - nut thread 3/4" x 16 part number 74039
Mercury & Mariner over 70hp - nut thread 3/4" x 16 part number 74039
Mercruiser Bravo III - nut thread 1" -14 part number 74053
Johnson & Evinrude over 140hp - nut thread M18 x 1.5 part number 74040
Johnson & Evinrude 40-140hp - nut thread 5/8" x 11 part number 74052
OMC king cobra - nut thread M18 x 1.5 part number 74040
Yamaha over 115hp - nut thread 18mm x 1.5 part number 74040
Volvo SX - nut thread M18 x 1.5 part number 74040