[Josh Grisdale]

If that is his weight and size, then the ones suggested by @allyhongo are probably the best.

Diapers are sold at stores here, even adult diapers for seniors. (Though, people with disabilities and seniors can get them for free from the city if they are a local resident.)

You may want to bring a stock of diapers with you though because depending on where your hotel is, there may not be a drug store nearby.