Does anyone understand how cell phone signal blocker sleeves work?

Normally those are just sleeves/bags that are lined with copper or other alloys in an attempt to block rfid and cell towers from tracking GPS, phone calls etc. They sell them to people by saying their credit cards are going to get compromised or your privacy through the speaker or cameras on your phone is at risk...which they are of you are giving permissions to apps etc to utilize those parts of your phone. Here is the thing though...most providers hire security experts that their sole job is to break the encryption on phones and computers and to find the holes before hackers do. That is why it is important to keep your phone updated to get the security patches etc. I'm more worried honestly about the fact that Congress recently rolled back the internet privacy act and your provider can utilize your data for another source of income. Wow the mountain lady has a SW account and boy does she talk a lot to her friends... let's sell her to a web browser company to try to get her to download a faster search engine.... or man she is asking questions about internet security... let's sell her number to an antivirus Corp so they can try to make a sale. Those are just examples but you get the idea. In dealing with security.... Don't use your credit/debit cards.... Get a prepaid card and link it to PayPal for convenience and only put funds in it when you expect to purchase. Then they'll only have a small amount to steal. As far as privacy that is a reason that a lot of people like phones that you can pop the battery out of but if you can't then pop the SIM card if you don't want anyone to see or hear what you are doing potentially. I have seen a lot of mixed reviews on the sleeves. Some people love them but there are many others that have reported they were useless to them. I'm not sure what the clip would be because most of them just fasten down. It may be for clipping the case to your clothes to carry it or maybe to make sure the,case is securely closed.