need replacement for 45W mag safe power cord for macbook air

Find the right power adapter and cable for your Mac notebook - Apple Support

You may need MagSafe or MagSafe 2 depending on the age of your MacBook Air. The cable that goes to your Mac is directly connected to the charging brick, so you must buy a new charger.

MagSafe 2 (2012-2017)

https://www.apple.com/shop/product/MD592LL/A/apple-45w-magsafe-2-power-adapter-for-macbook-air

MagSafe (2008-2011)

https://www.apple.com/shop/product/MC747LL/A/apple-45w-magsafe-power-adapter-for-macbook-air

Sorry, it's unclear what you're talking about. These are the parts:

The 'part that plugs into the computer' (the actual MagSafe connector) and the cord going from the MagSafe connector to the AC adapter (power brick) are all one part, they cannot be separated and you cannot buy them separately. When you buy that part, it includes the two-prong AC plug connector (sometimes called a 'duckhead'), and the prongs on that are specific to the country so in the US it's a two-prong plug but in the UK it's a three-prong plug for the outlets there.

Apple does not include the three-prong, grounded cord with separately-purchased adapters, and they no longer include it with the new Macs, either (but they do sell it separately).

i had to replace my 2010 MacBook air chord twice, one from apple and one from amazon

the amazon one held up better than the apple one, which i had to trash this year.

even the innards from the amazon were solid and safer with enclosed transistors and packaged better.

the price was much cheaper and same wattage and chord lights.

i even purchased one for my spare MacBook air that is holding up very good.

my advice is to purchase one with 5 stars and great reviews, and that has a conformable warrantee.

many  user purchase 3rd party items including batteries and chord for their MacBooks for over 15 years.

i hope this helped

OWC macsales has a adaptor: https://eshop.macsales.com/item/Apple/MD504LLAU/

this is the best i can do.

my power chords i purchased do not have the extra 3 prong chord, only the 2 prong.