SL-SF02 Spectacle Frame Bridge Deformation Tester Pneumatic Lens Retention Test Machine The SL-SF02 Spectacle Frame Bridge Deformation Tester measures the frame's lens retention ability, ensuring the frame can be safely worn for 2 years or more and preventing lenses from falling off due to slight impact. Key Features High Precision: Pneumatic device with 5N maximum pressure and electronic display with automatic timing for accurate, repeatable results Standards Compliant: