Soft thermoplastic rubber tipped temples grip lightly to ensure proper location of the optics without slippage. Aluminium-magnesium frame construction generates proper strength and optical stability through a hybrid lightweight metal alloy. Hidden spring hinges flex to ergonomically fit a wide variety of head and face shapes. Lightweight construction and proper weight balance guarantee long wearing comfort without pressure points or fatigue. Micro-engineered lenslocks securely retain lenses without undue stress or distortion of the optics.