Invoking the power of the lazyweb

I recently saw an ad three or four times on some website for a kit you could use to convert a cat or small dog carrier’s door so that it only opened if the approaching animal was wearing a collar with the right tag. I think it used RFIDs and you could buy just the converter kit or you could buy the whole carrier. That way you could keep the dog from eating the catfood or keep fat cat from eating skinny cat’s dinner, or just generally let fluffy get a break from barky if he needed it.

Saw someone online today who could probably use it — you think I can find the ad now? Nope. Might need one or two of these myself some day. Anyone know what it’s called and where I can find it?