The Energizer 370/371 is a high performance multi-drain watch battery. Multi-drain watch batteries perform equally well in low-drain and high-drain watches.
The size 370 and size 371 watch batteries are identical in size and voltage. The 371 is optimised for "low drain", while the 371 is for "high drain" applications. "High drain" means the bursts of power required e.g. when you press the light button on your watch. Because the 370 does everything the 371 does, and more, Energizer has streamlined production and now only makes one battery.