https://www.futureelectronics.com/npi/panasonic-pan1782-bluetooth-low-energy-module . Meet the new Panasonic Industry's R35K Narrow (Fine) Pitch Connector Series, which comprises an ultra-small connector pair with a pitch of 0.35mm. Panasonic Industry R35K Narrow (Fine) Pitch Connector Series is well-suited for wearable and hearable devices, such as side switches, battery, or sensor module connectors. https://youtu.be/_IlY02ZZD1c .