Butterfly Metal Detector Search Coils

Two D Windings, One Wide Field

Look at a butterfly coil from above and you see the trick: two D-shaped windings bowed away from each other, joined at the middle. Each D pushes its field outward toward the tips, so the effective sweep width grows well past what the coil's weight suggests, while the central overlap keeps a defined line down the middle for pinpointing. It is the same overlap principle as a standard Double-D, stretched sideways for coverage.

Coverage Plus Big-Target Depth

The reputation SEF coils earned in the relic fields is straightforward: wide passes that eat ground, and strong depth on larger conductors like large coppers, buckles, and caches. On small shallow trash the flared field is less surgical than a slim elliptical, and that is exactly the trade a field hunter wants: fewer passes to cover an acre, with the deep large target being the one worth the walk back. As always, real-world depth depends on ground, target, and settings, not the sticker on the shell.

Butterfly, Round, or Elliptical?

Choose by the job. Maximum depth for the size and the most predictable field: round. Separation in trash and reach into tight spots: elliptical, or the semi-elliptical middle ground. Covering open acreage with depth on the big stuff: butterfly. Most butterfly coils are aftermarket builds made for specific detector models, so confirm fitment before ordering.

Fitting One to Your Machine

Detech builds SEF variants for many popular platforms, but a coil made for one brand fits nothing else, so match the exact model and connector. Start from all search coils to filter by your detector, lean on our Search Coil Selection Guide if you are between options, and if the kit is growing anyway, the detectors and pinpointers pages round it out.