We have done all the countries around SA and have never had a ZA sticker on the bikes, and have never had a problem. What I have done though is I had a small one made up, same shape as the big AA one, and stuck it on the bike. What you can do is buy the big ones and take them with you, if you get stopped you just ask the cop where he thinks you should stick it.(nicely

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I have heard they can klap you with a lekker fine if you don't have one, and they will often try and sell you one right there at a moer of a price, safer to just carry one with you.