multiple external url for single product in woocommerce

I am working on a e-commerce site using woocommerce, I need a help guy, please see the following URL
https://www.aukey.com/products/bluetooth-keyboard-km-b9

You can find there are so many external link as dropdown, user can choose one link click on the “Buy on Amazon” button, I need a similar type of functionalities in my site
http://trodeemtech.com/product/bluetooth-keyboard-km-b9/

It’ll be okay if it’s not as similar as this, just help me with “Multiple external link for a single product”, It’ll be helpful if it’s a free plugin.
Thanks in advance

The page I need help with: [log in to see the link]