FREE Shipping! Complete UV housing assembly kit. Includes UV-kill 4-pin lamp. This kit will fit all units ordered in and after the year 2011. What is the difference between the pre-2011 2-pin UV lamp and the new post-2011 4-pin UV lamp? Just a slight upgrade in quality and improvement of a new solid state transformer. The transformer has 4 pins, so the UV lamp now has 4 pins instead of 2 to make the connection. All UV units made in 2011 and after will come standard with the 4-pin UV lamp and transformer. If you have a pre-2011 UV unit, you may upgrade to the 4-pin assembly easily by clicking here. Compatible ONLY with EWS under counter filtration units with UV, and reverse osmosis systems with UV.