I don't know about you, but after I mounted my AMS Lite on top of my A1, I was constantly confused about which slot was which!
Here is my solution for this - simple number tabs that attach to the front spool holders. They clearly identify the 4 slots by using large numbers for the front, and small numbers for the back.
Now, the spools rotate, meaning the numbers will not always be straight, but the small and large number system is obvious which is which.
At a quick glance you will be able to quickly identify which slot is which.
Important notes
Tip: when choosing your colors, pick ones which strongly contrast with each other. The whole point is to quickly identify which slot is which.
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