As others have said, they take your money (usually more than you thought!) and never deliver.
Everyone should avoid ANY Facebook "Sponsored item" which direct you to a website such as bit.ir/.... (or similar). Do not try to buy anything from a site which does not display a full website address (and make sure that when you click on it, it actually takes you to that website!)
Kigsgoshop.com sent a receipt written in broken English, confirming the price that the advert said, but warning that exchange rates etc might result in a small difference. My order went from $159.87AUD to $211.87AUD when shown on my credit card statement!
There was a detailed record of delivery' including "delivered to doorstep". But well before then I had given up hope of ever receiving the item, and had informed my credit card issuer a few days after I placed the order.