An loading material mechanism which USES the material of the electronic product - sheet material to make the sheet material through a special mechanism similar to the gear.The upper part of the body is designed to be special. The top wire is used to make a porous mechanism. The top wire is transmitted through the hole through the hole.It is clever to set up a special adjustment mechanism, because it has too much overhead and to ensure that each length is equal.if you like,you can paypal for you to get this models or if you have any questions also you can email to me.