I bought this to replace an old Sunpark SL15 ballast that was used for 2 round bulbs with T9 fittings. As shown in the picture, the old ballast (pictured above) has two 4-pin T9 sockets that connect to 4 pins on the bulbs. However, the one I bought (pictured below), which looks like a new design, has a different wiring pattern and doesn't have two 4-pin connectors, so it's not compatible with the old design. Sunpark did a really lousy job replacing an existing product, they drastically changedβ¦