Binder Clips
Staples & Clips · 7 specs
Direct Answer
The Binder Clip (Foldback Clip, invented by Louis E. Baltzley in 1910) is a reusable sheet fastener consisting of a tempered spring-steel triangular clamp and two collapsible nickel-plated wire loops. Available in standardized widths from Micro (1/2" / 13 mm, 30 sheets) to Extra Large (2" / 51 mm, 240+ sheets), it binds thick documents securely without punching holes or damaging paper fibers.
Source: US Patent 1,002,488 / Commercial Office Fastener Standards · Last reviewed Aug 28, 2026
Specs
| Micro Size (1/2 in) | 13 mm width — 4 mm capacity (~30 sheets of 80 gsm paper) |
| Mini Size (3/4 in) | 19 mm width — 8 mm capacity (~50 sheets) |
| Small Size (1.0 in) | 25 mm width — 10 mm capacity (~80 sheets) |
| Medium Size (1.25 in) | 32 mm width — 16 mm capacity (~140 sheets — most popular office size) |
| Large Size (1.6 in) | 41 mm width — 20 mm capacity (~190 sheets) |
| Extra Large Size (2.0 in) | 51 mm width — 25 mm capacity (~240+ sheets) |
| Material Composition | Heat-treated spring steel body (black oxide coated) + nickel-plated steel wire arms |
Mechanical Lever Advantage
The wire handles act as class-1 mechanical levers when pinched open to spread the spring-steel jaws. Once clamped onto the document stack, the handles fold flat against the paper surface for compact storage or can be completely detached to convert the clip into a permanent low-profile binding clamp.