The Mini 2000's infinity prism floats a stable, accurate bearing that appears in perfect focus~even when you're sighting objects miles away. Phosphorescent night lighting requires no batteries, but must be "charged" by placing the compass under a strong light. Protected by a soft rubber case. Configuration: Puck style Sighting System: Infinity prism Illumination: Phosphorescent night lighting Dimensions: 1 3/16"H x 3 3/16" dia Material: Soft rubber case Lanyard: Yes Batteries: Not required Included Accessories: Neck lanyard Warranty: One Year