【What You Get】The set includes 6 pieces Corner Guide and 1pcs 5-in-1 Book Cover Guide,that adapt to different sizes in order to adapt to the different thicknesses of cardboard,the sizes being 1mm,1.5mm,2mm and 3 mm 【5-in-1 Book Cover Guide】This set of rulers will help you in your bookbinding work, from cutting the corners to positioning the cardboard correctly. You can also use it to cover all types of album covers, make spine structures, double covers, etc. It contains an instruction manual with information on how to use the rulers included in the set. 【Premuim Material 】The Corn Guides are made of durable plastic and The 5-in-1 Book Cover Guide is made of durable metal stainless steel,which are not easy to break.suitable for you to use for a very long time. 【How Use the Corner Guides】Place the cut pieces of cardboard in the notches of the corner piece so that they form a corner. Then, place the other corner on the other end of the cardboard and repeat this step with the rest of the corners. Finally, use a cardboard glue to join the cardboard together and you're done! 【Wide Application】The guides are perfect for holding corners together while you wait for adhesives to dry.It can be used on book covers, boxes, dioramas, and more.