About the 11w Laguna Single-Ended UVC Bulb - BOGOF Manufacturer: Laguna ADD ONE 11W BULB TO YOUR BASKET AND RECEIVE TWO!!! This bulb is specific to Laguna and is particularly unique as it is both single-ended and single-tubed, with all 4 pins on one end. It is used in the old style Laguna Pressure-Flo 3000 & 6000 Filters. Please check the style of the bulb in your existing unit before committing to a purchase.