Bill

Water pushing against the bill is what drives a crankbait down and gives it its side-to-side roll. A short, square bill angled steeply down runs shallow and deflects hard off wood and rock. A long, rounded bill angled forward slices deeper and tracks more smoothly.

Bill shape also decides how snag-prone the bait is. A wide squarebill hits an obstacle and kicks the lure sideways, usually pulling the hooks away from the branch. A narrow deep-diving bill knifes down into rock and wedges.

Jerkbaits carry a small bill for the same reason, used to drive the bait a few feet down and hold it there rather than to dig.

Bill material changes the feel more than the depth. Polycarbonate is the standard and transmits vibration clearly. Circuit board lips are thinner for the same strength, which lets a bait start diving sooner, and metal lips turn up on older and specialist baits.