Throughout the years regulators have been upgraded and redesigned, every step and every upgrade is one step closer to getting a better flow of air and better comfort that also increases durability. As a scuba diver you will always have 2 regulators in your total diving system. The primary regulator is the one that you will be breathing from, the secondary regulator is +- 30cm longer in hose length so that your buddy can breathe from your cylinder while still remaining within reach of the air sharing buddy.
A buoyancy compensator is one of the most important piece of equipment in the diving career. There are quite a few styles out there and choosing one is a very important step to having a lot more comfort and stability while diving.