Found 2 exchanges where OKB is traded for BTC. According to the data on 25 July the most optimal price to exchange OKB for BTC is ₿0.0013 for 1 OKB. This rate is fixed at OKEx at the maximum trading volume of the pair OKB/BTC - 0.3 BTC.
The maximum daily trading volume is observed in the OKB/USDT trading pair at OKEx and reaches ₿ 69.72 (0.436% of the exchange's total trading volumes) at the price ₿ 0.0013 per 1 OKB.
The minimum price to buy OKB for BTC is 0.0013 - on the exchange OKEx.
The maximum price to buy OKB/BTC is 0.0013 - on the exchange CoinEx.