Universal Level-Ett DM101 Ladder Stabilizer

Amazon.com Product Description
The Universal Level-Ett ladder stabilizer eliminates the use of dangerous leveling items such as boards or bricks. It extends aluminum and fiberglass extension ladders up to a maximum of 9-1/2 inches. The stabilizer attaches quickly and easily with eight bolts (included), and features lever-pins, which allow easy height adjustment, and anti-slip feet for added safety. This ladder stabilizer meets ANSI and OSHA standards.
Universal Level-Ett DM101 Ladder Stabilizer