Allison Transmission Holdings, Inc. and its subsidiaries design and manufacture commercial and defense fully-automatic transmissions. The Company manufactures fully-automatic transmissions for medium- and heavy-duty commercial vehicles and medium-and heavy-tactical the United States defense vehicles. The Company operates through manufacture and distribution of fully-automatic transmissions segment. The Company's transmissions are used in a range of applications, including on-highway trucks (distribution, refuse, construction, fire and emergency), buses (primarily school, transit and hybrid-transit), motorhomes, off-highway vehicles and equipment (energy, mining and construction) and defense vehicles (wheeled and tracked). The Company's transmissions are sold under the Allison Transmission brand name and remanufactured transmissions are sold under the ReTran brand name. The Company has developed over 100 different models that are used in over 2,500 different vehicle configurations.