These dual carriage mechanical linear actuators are preassembled and ready to use. Synchro-use actuators connect at the linkage shaft to be used in pairs. The synched carriages on the two units move along with the rotation of the single shaft. The two carriages on each actuator move toward each other when the handle shaft is turned clockwise. The two carriages move away from each other when the handle shaft is turned counterclockwise. They can be used with simple manual adjustments without complex processes of parts selection, design and assembly. Link MAU5040DW shaftless actuators with MAU5040DW-Y shaft-equipped actuators. The internal parts are protected from dust by an aluminum profile body and dustproof sheet. The body is made from A6N01 aluminum. End plates made from chrome-plated die cast zinc. The shaft is made from 1045 steel with a black oxide finish.