3 Set 3 Ring Binder Mechanism Iron Loose Leaf Book Binder Ring Binding Mechanisms Replacement Set Metal O Rings Binding Spines Combs for DIY Making School Document Organization [3 Set Binder Mechanism]: Package includes 3 set 3-ring binder mechanism about 27.8x2.6~3.1x3cm(10.94x1.02~1.22x1.18in), hole: 0.5x0.4cm(0.2x0.16in), inner diameter: 2.57cm; screw: 0.95x0.8cm(0.37x0.31in), pin: 0.3cm; nuts: 0.8x0.35cm(0.31x0.14in), hole: 0.3cm. [Iron Material]: The binder rings mechanisms are made of iron, which is not easily broken or faded. It is sturdy and durable, and the circular ring allows you to quickly scroll through the pages. [Easy to Use]: The metal loose leaf ring can be divided into two halves. Place paper with holes into the ring and then close the circular ring. The book binder is securely locked to prevent the paper from falling off or loosening. [DIY for Fun]: The 3-ring binder mechanism is very suitable for DIY. You can put different colors and shapes of paper into the circular ring, customize a notebook for yourself, and enjoy the fun of DIY. [Widely Usage]: You can not only make new notebooks, books, etc. with 3-ring binder mechanism, but also use them to replace old binder mechanism.