How can I check if 20w adapters are original or fake?
How can I check 20w adopters is original or fake
[Re-Titled by Moderator]
How can I check 20w adopters is original or fake
[Re-Titled by Moderator]
By purchasing from Apple - or an authorized reseller - and breaking the tamper-evident seals yourself.
Counterfeits can be - cosmetically-speaking - VERY convincing.
Your Apple device is quite “pricey.” The power adaptor is the ONLY thing standing between your device and “Mains” A/C voltage.
It would seem that skimping here is false economy and CAN be dangerous. See this article for an illustrative example:
http://www.righto.com/2014/05/a-look-inside-ipad-chargers-pricey.html?m=1
In addition to Chattanoogan's excellent reply, you may find the following helpful:
About Apple USB power adapters - Apple Support
How can I check if 20w adapters are original or fake?