I recently purchased a weather flow meter from amazon and it did not perform as expected when linked up to strelok. I sent the company an email and was informed that the newest versions of the WF unit no longer have an onboard compass. It relies on the phone compass. Therefor mounting a WF meter in a vane is now pointless, unless you also mount your phone in the vane as well. I expressed my disappointment and they offered to send me one of the older models in exchange. So FYI, if you plan to purchase a weather flow please contact the company and request an older version if they still have them. I am hoping they rethink their decision to ditch the onboard compass, as doing so has made the unit exceedingly less useful for precision shooting.