Answer for I bought 2 Luminus PAR 20 50W replacement dimmable to replace Halogen Floodlights 50W, 530 lumens. The dimensions are practically identical but the PAR 20 bulbs won't work when inserted into the sleeve which holds the fixture in the aperture or pot hole. The pot holes are 4" across, 4" deep and perhaps 2" at the base. From your information it appears I need a retrofit for each aperture or pot hole. We have 9 pot holes inn total and the plan is to replace each as the Halogen bulbs burn out. Questions: Do I have the correct replacement with the PAR 20 bulb? What is the cost for each retrofit kit? We bought the 2 PAR 20 bulbs at Costco, St. Catharines, for about 19.99. Seems reasonable but still pricey. Any advice will be welcome. Do you sell the retrofit kit? Thank you. Keith Rae