It is new and original to design ，The second track adopts the broad gauge design ，Adopt the self-regulation double round composition idle wheel 。 Open agilely ，Does not there is not noise 。 The inside and outside circle adopts the different one kind of mould material compose 。 Manufacture simply ，Association is beautifully 。 Assembleeing to adopt the maneuver horn code connections ，It is easy to be convenient 。 Assembleeing to adopt the maneuver horn code connections ，It is easy to be convenient 。 Fix raiseing the utensil drawing ，May manufacture to raise draws the window 。