Ok. So I have a bunch them here, different sizes, both SSD and spinning rust. The big ones are all consumer grade drives with a little adapter board like you describe. The small ones are a mix of a single custom board with a USB connector and adapter board based ones. The tell tale is the outer dimension in the length, if the case is a little bit longer than a standard drive you have a very good chance of having one with an adapter board if it is the same or even smaller than the standard format then almost all of them are custom boards. The really nice ones have NVME guts in them that you can immediately repurpose.