QRPLabs sell even lighter trackers https://www.qrp-labs.com/u4b.html https://www.qrp-labs.com/u4b.html and AFAIK are the goto supplier for HAB (High Altitude

QRPLabs sell even lighter trackers https://www.qrp-labs.com/u4b.html https://www.qrp-labs.com/u4b.html and AFAIK are the goto supplier for HAB (High Altitude Ballooning) enthusiasts.