Unfortunately looks aren’t everything; if you want reliable 2.4 GHz triggering you still have to stretch your wallet an extra $16.00 for the Yongnuo RF-602 instead.
All IShoot branded triggers (PT-04 CN, B, C and A) are confirmed inter-compatible, but they are not compatible with other triggers.
The information on the PT-04 box mentions an unreleased PT-04 D as well. Which shape haven’t they tried yet?
UPDATE on the PT-04 D according to eBay seller lilyrst:
it’s a new flash trigger which is being researched and developed, its working range possibly reaches 200m above. But that really need a little longer time to make it perfectly.