macbook air battery replacement

Perhaps you may see listing for Battery from within About this Mac,

in System Profile; under the menu bar Apple. ~ That may identify the

Battery; should show the original Capacity and its present status.

Since each portable Apple product has specific 'service parts' by number

for their product; an Apple service provider, or retail Genius could assist

& determine your MacBook Air's status (Build/Year/Model: info required.)

..Many newer portable Macs have no user-serviceable parts..

• Identify your MacBook Air model - Apple Support

https://support.apple.com/en-us/HT201862

And you should be able to specifically Identify your MacBook Air, from

dozens of production build model years; in the wild, & in need of parts.