Otis Worldwide makes, installs and services elevators and escalators, the largest company in the world dedicated specifically to vertical transportation equipment, spun off from United Technologies to operate as an independent public company. Its business model combines new equipment sales, which tend to be more cyclical and tied to construction activity, with a large recurring maintenance and service business covering elevators and escalators already installed in buildings worldwide. The service business tends to generate steadier, higher-margin revenue than new equipment sales, since building owners typically maintain service contracts with the original equipment manufacturer for safety, liability and reliability reasons over the multi-decade life of an elevator. Otis's new equipment sales are tied to global construction activity, particularly high-rise commercial and residential building trends, while its service revenue benefits from the large and growing installed base of elevators it maintains worldwide.