Jimmer
Contributor
It all depends on how cold the water gets where you will be diving. For the temperature range that Byte Me refers to there is certainly no ned for a specific 'cold water reg'. Water temps where I am get down to a bit below 50 (46 would be the lowest) and I have dived these waters for 30 years without ever having used a cold water reg. None of the divers I dive with have ever had any issue with these temperatures and just about any brand or model of reg you care to use.
Unless you are diving very cold water below 45 then just buy whatever standard reg suits your needs best.
Yes, well the OP asked about cold water regs for the same area that I dive in, which can very easily hit the 30's. You need a cold water capable reg for that.