ya some net pots have tabs on each side so they don't fall through the holes, if you happen to drill them the same size as the cups. i played it safe and bought cups a quarter inch bigger than the holes i drilled. anything bigger and your cups will stick out more than they need to. this should be common sense though. as far as 'heavy duty' cups go, that sounds like a marketing trick. all u need are cheap ones, and they'll last you forever if you decide to re use them. now on to more urgent questions