For more than a year now, all boards, either the ones bought separately or as part of the starter kits, are the latest v0.5b. The only difference between the .5 and .5b is the power options for the bee socket via jumper SJ13 to give you the option of powering the bee socket either from 3.3v Vcc of the board (default) or directly from the LiPo socket if you cut the trace and add some solder to jump it to the LiPO setting.
I know I’ve posted in the forum about the change between versions, but I just noticed that it isn’t noted on the Mayfly jumper settings webpage, and the photo is of the much older v0.3 board. I’ll try to update those soon. Same thing with the Amazon photos, I’ll have to update those when I get a chance to take and edit new photos of the latest boards. I’ve just been too busy building and deploying new stations this summer, and keeping up with everything required for testing, prepping, and shipping all the new boards to Amazon.