Pynco offers a wide variety of ring filters, ranging in size, thickness, and glass or aluminum cap. When choosing a ring filter, you may want to consider: Can I use the most common, lowest cost ring filter for T-1 lamps (0.210 max. O.D). Or, do I need a special configuration? Do I need the smallest and brightest 5-Volt FLA (0.135 max. O.D. x 0.185 max. O.A.L.)? What are my power requirements (amperage & voltage)? Do I need polished for high transmission or will unpolished meet my needs? Do I need upper or lower Green "A"? Do I need Green "B"? Do I need wire leads or bi-pin? Do I want to explore LED illuminati