This pen knife (or perhaps flick knife) does actually open. For those with safety concerns, the blade is very (very) blunt. Unlikely people with safety concerns would want to wear these, but just to be clear: Not suitable for Children under 3 years old. Just like all our other cufflinks. Rhodium plated Dimensions (LxWxH): 19mm x 8mm x 4mm (approx.) Weight per cufflink: approx. 3.78g (light)