Springback Binders UK Archive Springback Binders 25mm size can hold from 1 to 150 loose sheets, or 3/4&quot; Circa discs (up to 120 sheets). 50mm size can hold from 1 to 250 loose sheets, or 1&quot; Circa discs (up to 150 sheets). Grasping firmly, turn the cover inside out to open the clamp. Place your disc-bound Circa sheets inside, then release the clamp. To secure loose sheets, just slip them into the included folder, then clamp inside the cover.