Forgive the large photos and long post.   So you have an itch for a MarineMaster 300 but don't know whether the $2600 MSRP for the SBDX001 is worth it, or whether you could get an EXACT copy for $260 from Sharkey...   Well let's start by meeting our challengers.     The initial impression is that they are very similar and one might look at this photo and say "Same watch, different name".   They have the same Vibe, the same shape, the same dial layout, the same bracelet pattern. It would be easy to dismiss the cost difference and happily save the $2240 off the MSRP, but given the age of the MM300 (SBDX001), there are ample sources of second hand versions ranging from $1200-$1800 depending on the kit, which means the REAL cost difference is somewhere around $1200.   Ok, Why spend the $1200? You get a better watch. Not just mechanically with the Seiko's 8L35 movement, but also the finish and the fact that the un-seen portions of the watch (Seals, gaskets, etc) are ISO rated for 300M verses the Sharkey's 300M label.   Let's move on to some portions of the watch itself.   1. Springbars.   Sharkey on the Left, Seiko on the right. Note that my Seiko is second hand and old, and the Sharkey is brand new.           The Sharkey springbar is slightly longer. You can see a difference in the machining on the part, so it's easy to say that the Sharkey doesn't use Seiko bars in their watch.   2. Bracelets.   The SBDX001 gets alot of hate on the size of the clasp and the "Gaps" between the links.   I sized both bracelets to fit my own small, 6.5" wrists. You can see from the first photo that the lengths are the same. What is interesting is the differences in lengths when the clasp is open.     In the following picture you can see the clasp on the Seiko opens up wider, allowing a larger hand to fit through comfortably.     The Seiko's ratcheting dive extension further extends the difference.   Continued....