D-BHB is the ketone your body produces from fat to use as energy. Since your body naturally produces D-BHB, when taking it in supplement form, the bioavailability when compared to the other exogenous ketone supplements on the market is far greater. This means that the D-BHB will get absorbed into your system faster. D-BHB alone is more expensive and harder to produce than general BHB which contain both L-BHB and D-BHB. Because the extra and special process need to be increased for producing D-BHB.