optically clean
doubles AF-S 200-500/5.6 to 400-1000/11, AF sadly doesn't work but VR still ok
likewise it works with AF-S micro 105/2.8, AF doesn't working below around 1:1.4 as the effective aperture decreases and drops below the working threshold (slower than without TC above 1:1.4)
Please check compatibility before buying. For example, it won't fit AF-S 28-300mm G or AF-S 24-120mm 1:4 G