The most popular choice: Expandable Kitchen Storage Rack with Adjustable Shelf Dividers for Seasoning and Cookware Organization. Made of durable plastic, this Countertop Cabinet Organizer requires no assembly and features layered shelves and a convenient

I didn't even realize they were extendable. PERFECT, and also slightly height adjustable. I was going to put them in a kitchen cabinet, but they fit great in the IKEA shelf too 👍👍 I've already ordered more.

Assemble it, put it in the cabinet, and the 2nd level is ready.

When buying was hesitant if the construction is strong enough for dishes. Appeared to be solid. In my case I extend it just for 8-10 cm to fit into the shelf and it handles weight well. Probably if you need it for a bigger extension it might be flimsy under the weight. For my use case is perfect

already a subsequent purchase. I now have a great order in the cupboards.