1504/826 is for the pre-ceramic chronograph,
1515/816 is for the 2012 ceramic (regular, no chrono)
Afair these endlinks are not interchangeable. What model you have?
Here is the link to the watch I have on order in both Blue and Grey. Everyone is saying the bracelet that comes with the watch is wrong so I was going to buy a gen bracelet. I tried using the model number for the Omega Seamaster Diver 300 M Automatic 42mm Blue Dial Men's Watch 210.30.42.20.03.001 to determine the bracelet but it is not much help. 30 only means it is stainless.
https://puretime.io/featured-produc...e-ceramic-gray-dial-on-ss-bracelet-a8800.html