Compatible with Hawke scopes: 16120, 16121, 17100, 17110, 17120, 17130. Please note, metal flip-up covers are not compatible with the Frontier 30 range or XB/XB1 crossbow scopes. Produced from high grade aluminum. Easy to operate using one hand, the covers are designed to protect the lenses when not in use. Covers are easily installed and can be securely positioned to open in any desired direction.