The PD-1617 is the older "Aquaracer" homage watch and suffers from some quality control issues and overall quality issues the newer ones don't have. They have the Seagull movement which isn't as good as the Seiko used in the later model. My two keep time to +- 1 minute per day which isn't that great. The Seikos seem to hold to about 15 seconds at most. I had one which I had to return because the rotor was hitting the case back and rattled badly, Also, they have the mineral glass crystal and not the synthetic sapphire like the new one. Some are marked 30m and some 100m water resistance but seem identical otherwise so who knows what the real ratings are. Some have misaligned bezel inserts. All in all I would recommend the newer PD-1668 version.