Recently I bought the Zhongyi lens turbo II M42 to M43 adapter. Later more about my experience with this adapter, first an explanation why I bought the Zhongyi. The Zhongyi lens turbo adapter costs 149 USD (that was about 130 euros with the exchange rate at the time I bought it). It is certainly not the cheapest lens turbo adapter you can buy. You can even buy ones that are around 80 USD. But those are not well made and have lenses inside them that are not very sharp. The Zhongyi is quite a bit cheaper than the better known Metabones Speedbooster (which is about 3 times more expensive). But I've read that the Zhongyi holds up quite well against its better known and more expensive counterpart in the results it produces.