If you want to use an iPad you can choose:
The Group Fitness Blue (for personal trainers, about 5 people)
The Group Fitness Plus (for clubs and gyms)
The Group Fitness Blue works with any Bluetooth Smart HRM
The Group Fitness Plus works with Polar Bluetooth HRMs and ANT+ HRMs. With an iPad, to use ANT+ HRMs you should use our Selfloops repeaters.
The Group Fitness Plus for iPad supports the Polar H7, Polar H10, Polar A360, Polar A370, Polar M200, any other Polar sport watches with optical heart rate monitor and our HRMs.
This is a comprehensive list of ANT+ HRMs: http://www.thisisant.com/directory/selfloops-group-fitness