Must be a mistake on Casio's site, because no way is it any heavier (much less +50%) than a Frog, which has a screwdown caseback. They list this one at 132g though. Looks like the same mistake on the gw9000a mudman too (132g). That's more than 2x as heavy as the riseman and gulfman (no way), but I.D.K. where they are coming up with 132g for these two.