My favorite medium sized light is now my newly modified SK-58. It has a Nichia 219B neutral white high CRI LED and the components of a Qlite driver on a BLF SK-68 15 mm. board, with moonlight mode group selected and four 7135s. The 15 mm. driver makes room to make thermal contact between the pill and the thick battery tube (where the fins are on an SK-68). (See sk68 clone: longitudinal section) To bridge the gap, with limited tools and materials, I twisted stranded copper wire in a loop, saturated it with solder and shaped it to fit snugly in the space. It draws 1.8 A on high, which seems enough for the little Nichia and low enough not to need the extra metal and fins of an SK-68.