[F][P] DIY Media for a wet/dry

I have nearly completed my DIY wet/dry filter and am now deciding on
what types of media to use.
I recently saw some 'practice golf balls'.
they are the same size as normal golf balls but are hollow and have
holes all over them. the holes are about 5mm in diameter.
they are also made of a white plastic.
would these work as media?
the tank is a 55g and the wet/dry will hold about 15 litres of media.

thanks in advance
stevendi at ozemail_com.au