I have personally tested these often with 13 of our wide (62mm) thick plastic star design cards whilst playing kalooki with my family. There are two pieces of smoothly well finished clam shaped plastic that is spring loaded and unless I drop the whole card holder then I don't think any of us have ever had a card drop out. Four card holders are in each pack and come in 4 different colours so the only problem you might face is going to be about who has what colour. Last stock I opened to use contained Orange, Blue, Green and Red but this may vary in future.
Written by Simon Rush.