I've been using the kayfun top fill by steam tuners for a couple months now and I cant go back to the original kayfun topcap, its just so convenient and looks so good. Steam tuners nailed it. Ive used multiple liquids including lemon, pony on acid, pink lemonade, mixed berry and a few more and haven't had any issues with cracking unlike the kayfun bell that cracked within a week.