Flutter offers two control modules - the Basic and the Pro. Both boards are identical except for two features: the Pro has twice the flash memory and RAM for larger applications, and the Pro features an external antenna for over 1km range.
Notably, the Pro also ships as a partially assembled kit rather than a complete product. The Pro Kit comes without the antenna or pin headers soldered on, to allow maximum flexibility for the user. The Pro Kit requires some basic soldering to attach the antenna, while the Basic is fully assembled and no soldering is required.