I purchased a router bit that was advertised as being suitable for cutting a slot for a woodworking biscuit. Biscuits are 4mm thick, however the router bit only cuts a 2mm slot, obviously useless for what it is advertised for. Yes you can do 2 cuts to get to 4mm but that all takes time & negates the advantage.
The seller didn't reply to my last message where I pointed out the discrepancy & Aliexpress could care less. They also don't use Paypal who are very good at refunding for dodgy purchases. My advise is to use Banggood or Ebay for who both have similar or same products/prices & who both use Paypal.