Compatibility: Maximum is gratifying that I tolerate well. I have a strong allergy to nickel and probably another metal, as I myself have got rashes on allegedly nickel-free products. Not at this clock. Even when wearing all-day I see nothing at all.
Comfort: Due to the metal bracelet the clock is secure enough to avoid slipping and yet "sticks" they do not like a lot of leather bracelets do it on your wrist. The price-performance ratio is very good.