The Scosche RHYTHM+ is a Bluetooth and ANT+ optical heart rate monitor that is worn on the arm.
Positives: It is the most accurate optical HR sensor I’ve seen (September 2015-March 2017). It’s comfy and easy to pair with numerous devices. Battery life is over 7 hours. It is ANT+ and BTLE compatible.
Negatives: It’s a bit expensive but then so are many other HRMs. Not sure how long the strap will last but many chest straps pack up after a couple of years – the strap should last at least that long!
Comments: These work great on your wrist, forearm or upper arm and could even be worn by smaller wristed people like kids! I noted a high level of accuracy against top level chest straps.
Alternatives: MIO’s wrist worn bands; chest straps from many vendors from Wahoo to Garmin, 4iiii, Polar, Suunto and others; HR earbuds from JABRA; and I think you can even get helmets/hats that read your HR.
Detailed Review: This link covers my detailed review of Scosche RHYTHM+