Associated Engineering Works manufactures various types of gear roll testers that they claim have advantages over competitors' models. Some key advantages highlighted in the document include the use of hardened steel slides and guideways that require less maintenance than cast iron components, a foot pedal for operating the moving block, and a live spindle arrangement that extends the life of master gears. The document provides details on the types of testers manufactured, such as models for plain or centered rolling of small or large gears, and lists satisfied customers of Associated Engineering Works.