My 5-year old boy wets his diaper most nights. We'd like to train him to hold his urine or get up to use the toilet, but he is a heavy sleeper. I've read that alarms which detect urine can be effective in eventually training a child to anticipate urination and awaken. Have you seen such alarms for sale in Hong Kong? There are plenty of online sources, but I'd prefer to have a physical look at one before buying it.