【5/16 inch,40 Sheets Capacity】: HOUYEE plastic spiral binding coils, with a diameter of 8mm (5/16 inch), securely hold up to 40 sheets of paper. This set provides 4 different colors of spiral binding coils, totaling 50 pieces, packaged in black binding coils 20 packs, blue binding coils 10 packs, red binding coils 10 packs, clear binding coils 10 packs. 【4:1 Pitch, 48 Loops】: The spiral binding coils have a 4:1 pitch, making them compatible with any binding machine that punches 4 holes per inch. (Note: These 4:1 pitch binding coils are not compatible with cinch machines, comb-binding machines, or wire-binding machines. They are for spiral coil binding machines only.) 【360-Degree Rotation】: The plastic spiral binding coils offer a 360-degree flip-and-rotate function, allowing bound items to lie flat. You can easily add or remove pages for convenient binding and reading. 【Letter Size, Premium Material】: These 48 loops binding coils are suitable for letter-size paper (8.5 x 11 inches). The length can also be freely trimmed to meet personal requirements. Our binding coils are made from high-quality plastic, ensuring strength and sturdiness. 【Widely Used】: The plastic spiral coils help you organize messy documents and maintain order, making them perfect for office files, home, education, business presentations, and more. They are versatile and practical, ideal for assembling report pages, calendars, documents, etc. This also makes them an excellent gift for teachers, students, and colleagues. HOUYEE Binding Coils 4:1 Pitch Letter Size, 8mm(5/16"), 40 Sheet Capacity, Multicolor Plastic Binding Spines/Spirals, (Pack of 50 Binding Coils) Plastic spiral binding coils from HOUYEE are made of high-quality plastic that wont bend or scratch. These flexible binding coils have 360-degree rotation to allow you to add and subtract paper sheets any time with ease. These plastic spiral binding coils are an excellent high-quality choice for business proposals, directories, staff handbooks, annual reports, company presentations, restaurant menus, and more!