Cosco aluminum multi ladder 9' step ladder 21' extension ladder and offset ladder for stairs model #20-C21 TIAS. This ladder is in great shape and hasn't been used much, only selling because I have too many ladders. Here is a link to a YouTube video of how the ladder works https://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwiRwOTRvoHvAhVYvJ4KHZ3BCMwQwqsBMAV6BAghEAM&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3D8yiykiY9Q5g&usg=AOvVaw2nktwhI3QS7fuhHtIB49zm