Recently I was present when an older over weight person had heart problems at a social activity. Experienced medical people were on the scene, but had no equipment with them. Having a first aid kit with me I loaned one of them my blood pressure cuff. Much to my surprise it would not fit, their arm was too large. They needed an extra large cuff. Prior to this incident I did not know they came in sizes. So if you have someone in your family or group that is unusually large you may want to check it out and make sure your cuff will fit.