Garmin HRM 3-SS will connect/pair with forerunner 35 but will not show heart rate (see picture) - Accessories & Sensors - Running/Multisport - Garmin Forums
Garmin HRM3 Premium – Incycle Bicycles
Original and New Garmin HRM3-SS Heart Rate Monitor Run Heart Rate for Garmin Forerunner 10 15 220 620 735XT 1000 Fenix2 Fenix3 - AliExpress