Crankbaits with square diving lips — aka squarebills — have become the go-to baits for many shallow water bass anglers. Designed not to acquire much depth because their lips are not as long as most curved- or round-billed crankbaits, squarebills are designed to deflect off cover — such as stumps or rocks — triggering bass to strike.
Many crankbait enthusiasts recommend selecting a bait that dives slightly deeper than the water being fished, which will cause the bait to deflect off the bottom and create that erratic triggering action throughout the retrieve. Most major crankbait manufacturers have squarebills in their lineup.
— Bob Gwizdz
