Stickers that show certification for that batch are supplied and when a customer requests proof of certification, a sticker is attached. Very few customers demand actual proof of certification so, stickers begin to collect after only a couple of batches. The problem is that in truth, most companies don't continue to submit samples for certification from each and every batch of oil they have refined because the certification process is expensive, it takes a lot of time, and the standards aren't difficult to meet.