These are GUARANTEED GENUINE Princeton Technologies PT2399 integrated circuits. We buy them through official channels, not through ebay or other gray-market resellers. These are the real deal.
The PT2399 IC is used in the GuitarPCB D'Lay project and numerous other delay and reverb circuits. Although patented, the Belton digital reverb bricks use 3 of these IC's to deliver high quality reverb.
Because we did not go through questionable sources to obtain theses, we purchased enough to sell with our D'Lay kits, as well as to sell separately in our store without a kit. Some of the ebay sellers are selling 1 if these IC's for less than we pay for legitimate IC's in quantity. I would say the chances that those are really Princeton Technologies products is extremely low.
Before offering kits, we built a lot of pedals, and found that the knock-offs just don't stand up to the real thing side by side. There are a ton of threads on the internet about where to get "real" PT2399 IC's because people were having questionable results when buying from questionable sources. Look no further!