Examining this MMI product vs. a home grown clone for example:
- Stainless steel vs. grade 5 steel in an area that is commonly wet and for us ocean guys, wet with salt water. If you think the lower bolt is hard to get to, try extracting a broken bolt stump that's rust-welded into the same location.
- A sealing washer is included. The home grown re-inventer usually uses a split lock washer then wonders why it leaks when it didn't before. See the first bullet point when that happens.
- Threaded portion length. If you read the link I provided earlier you'll read about the gear damage that occurs when the threaded portion extends too far into the accessory drive.
Like I said, MMI products are thoroughly thought out and perfect for our needs. As we are fond of saying around here,
"Do it right, cry once."**
** Credit: Dave Neptune