Easy to Use and Set Up: This extension ladder leveler sets up in minutes and requires no installation; it can be moved easily from stair to stair without hassle or effort. With their all-steel construction, rubber soles, anti-skid surface, and locking pins, the Ladder-Aide PRO can support Type III to Type I-AA extension ladders, while the Ladder-Aide SLM can support Type III to Type II extension ladders.