Crossover Subs are primarily used for a couple of purposes. They are used for crossing over from the size of a single connection to the other. Crossover sub is also used for prolonging the life of the more expensive components of the drill stems. Crossover sub is available primarily in 3 forms. The connections of the Subs are available in 3 forms, box-box, box-pin, pin-pin.  
LUHAI can provide AISI4145H and Non Magnetic material crossover subs.