Fitment -- 816607 Bellows Sleeve Ring fit for Mercrusier Alpha One Gen II 1991 and Up. Detailed model -- Our bellow retainer ring for fit for Alpha One (Gen II) 1998 and Up - s/n 0L100040 & Up, for Alpha One (Gen II) 1996-1997 - s/n 0F680000 thru 0K999999, for Alpha One (Gen II) 1991-1995 - s/n 0D469859 thru 0F679999. Replacement -- This for mercruiser alpha 1 gen 2 bellow retainer ring manufactured to meet OEM specification. Replaces for Sierra 18-1728 and 816607. Superior Material -- 816607 Bellow Flange Ring made of superior-quality Aircraft Grade Aluminum. Produced on precision CNC machine tools, and hard anode Oxidation treatment ensure an unparalleled long lifespan. Tips -- Our aluminum flanged sleeve ring can use with Bellow Retainer Ring in our store. Quickly and easily complete the job of replacing your old and broken Bellows Sleeve Ring.(Comes with installation instruction)