Well, if we were to be going to be analytical about it, the PAM305 is only rated to 300m, the PAM364 to 2500m, the difference in the depth rating would mean thicker crystal and a slightly taller bezel to contain the crystal, which would make for a slight increase in weight for the PAM364. Similarly, the PAM389, also a Titanium submersible at 300m depth rating, would be heavier than the PAM305 because it has an anti-magnetic faraday cage made of soft iron. But we are talking gens here. The reps might differ in the material and the amount used.