Coil bindig machine or the Spiral binding machine is very easy to binding,and the binding quantity is much than the others,for about 25 sheets,this machine is very popular in the binding machine market.Usually,the hole about this machine is oval,this is a new shape.The oval hole is popular in the U.S.A.
Compared with the round hole,this oval hole is better to insert the coil,you will found this is better to turn the paper.