LL-STB-1 leveler and stabilizer is the ultimate in extension ladder accessories: Easy to use. Easy to install. Tough as nails. And an army of telecommunications companies, utility companies and governmental organizations have - through their own testing - come to know the LL-STB-1 as the safest ladder leveler on Planet Earth. The LL-STB-1 is easy to use. It enables virtually any fiberglass, aluminum or wood extension ladder to adapt to nearly any indoor or outdoor situation - from stairwells to uneven terrain on job sites. Its unique, patented design can be operated using only your foot - freeing your hands to hold the ladder. It is precision manufactured from high-strength 6061-T6 structural aluminum (the same material used to build commercial aircraft). And its patented "Anti-Trip" automatic safety lock exceeds every ANSI and OSHA requirement for ladders up to and including Type 1AA ladders with 375 pound duty ratings. LL-STB-1 levelers are quick and easy to install. (In fact, they can be installed with simple tools in less than 15 minutes.) If you prefer, they can be pre-installed at the ladder factory, or professionally installed by local ladder dealers and service companies, such as Advanced Ladders, Batavia Services, Inc., Industrial Ladder, Nationwide Ladders and Ladder Doctor (all specialists in serving utility companies).