An applicator made of two loop coils connected and angled toward each other. The magnetic field focuses at the point where they converge. The two-loop construction lets the field enter the target area from both sides simultaneously. This produces a stronger, more focused field at the convergence zone than either loop would generate alone. Commonly used for joints and specific muscle groups where surrounding coverage plus focal intensity is desirable. Often referred to simply as a 'butterfly coil,' though the construction is two loop coils rather than a single coil.
Some accessories use a pair of loops. A butterfly coil angles two loops inward toward each other so their fields add up over one focused spot. A Helmholtz pair holds two matching loops parallel and about a radius apart, which makes the field in the space between them unusually even.
