Like a dyno, super accuracy is not that important for just monitoring, but consistency is. I've got a sphygmomanometer, but can't use it because of hearing loss. I used a wrist one for many years, I liked the ease of use, but not the batteries, and my doctor rolled his eyes, so when it expired got a rechargeable arm band type. This is really good, but in winter I wear too many clothes, I need to check bp with one layer at most. It takes more time to set up, leading to more stress and higher readings....the wrist type I would just leave on for 5 or 10 minutes and check whenever, and readings were lower when I did that. I use an app on my phone to record the data.