They are “reusable” plastic bags in the shape of Mason™️ jars. Cute.

I like my heavy duty FoodSaver™️ vacuum bags with the usb powered little vacuum. They make food last forever!

Cordless Mini Vacuum Sealer Machine, USB Rechargeable Vacuum Sealing System Food Storage Saver with 5 Reusable Storge Zipper Bags, Black https://www.amazon.com/dp/B01MZ7AK2Z/ref=cm_sw_r_cp_apip_Pv1bBD2NQJwK2