The ZeroTech 50mm (3a ^2) Sunshade is purpose built to shield the amount of light that enters the scope to minimize the glare, which can help your eyes and improve your accuracy. Fits the Below Models: Thrive HD 2.5-15x50mm PHRII 2.5-15x50mm Illuminated PHRII 6-24x50mm PHRII 6-24x50mm Illuminated PHRII Trace 3-18x50mm R3 4.5-27x50mm R3 Trace Advanced 4.5-27x50mm RMG