How to access Polygon (MATIC) mainnet through Metmask:
In your Metamask extension or mobile app go to settings.
From there select networks
Choose "custom rpc" or "add network".
Fill in these details accordingly:
Network name: Matic Mainnet
New RPC URL : https://rpc-mainnet.maticvigil.com/
Chain ID: 137
Currency symbol : Matic
Block explorer URL: https://explorer.matic.network/
From there hit enter or submit.
You have now connected your Metamask to the Polygon (MATIC) Mainnet.
Your Ethereum address will be the same as your Polygon (MATIC) address.