The symmetrical design of a dual caliper release head assures even distribution of friction which leads to enhanced bow tune-ability. Many archers prefer the larger dual caliper head as there is more head to wrap your fingers around. Dual caliper releases also offer more overall adjustability and are generally characterized by heavier trigger settings.
The Shark is the best-selling dual caliper SCOTT release. You'll recognize it because of its green jaws and trigger. You'll love it because it performs!