How to tell apart 5W power adapters without green dots?

[NOTashwin]

Apple recalled the 5W USB power adapters in 2008, so they started printing a green dot on all of the updated power adapters to tell them apart from the unsafe ones — but around 2013, the green dot stopped being used.

I have a box of disorganized Apple 5W USB power adapters. How do I tell apart the unsafe pre- green dot era power adapters from the safe post- green dot era power adapters?

 

[macbuzzr]

If You are located in Europe, this might help:

https://support.apple.com/usbadapter-european

The new ones should have "A1400" printed on the housing. A power adapter for my old iPhone 5s (2013) already has this label.