What is the first bit to use on a horse?

I'm curious, could you please clarify what you mean by "the first bit to use on a horse"? Typically, in the world of finance and cryptocurrency, we don't often discuss bits in relation to horses. Are you perhaps referring to a specific type of technology or equipment that utilizes bits, but in a context outside of the traditional finance or crypto realm? If so, I'd be happy to try and provide an answer that aligns with that context, but it might require some clarification first.