Instruction: Answer the given question by extracting information from the supporting document.

Input:
Question: Can anyone confirm if this is using  the older/thicker copper coil system or the thinner printed circuit?
Document: The item was as described (the plastic printed card, not the copper coil) I took off one of the stickers and it fits under the original back with no bulge. I used electrical tape to hold the contacts on and it fits, no problem.
Rather than give Samsung $40 for a thicker cover, this worked perfectly for allowing me to keep my LifeProof case. It's thin to the point where the case fits perfectly without a noticeable bulge, and NFC works perfectly. Though the older reviews mention how the labels on the coil block NFC (due to being plasticised aluminium), it seems they updated the design recently (the labels are now non-metallic stickers; I checked by partially removing one side).
FRAUD!This receiver is not the ultra thin version in the pictures, as advertised. It is the standard copper coil product. It works perfectly fine (including NFC), but is not as adevertised.
Not a big deal because the blackberry cable is very thick.- 600ma output as some other models you find say 1000ma(I think those are thicker though)Bottom Line- Pretty hard to get thinner than this.- Does get warm to energy loss through heat dispensation.- Be careful, the look and packaging is copied in China and look identical to the original.
"Warning to everyone.The coil sent to me was not the one pictured, it is infact the one with the thick copper coils which the the seller advertises it is not! [...] outlines the differences. I recommend people stay away from this product if they want the genuine fonesalesman product.I paid extra to get the fonesalesman version and this item is not it.Fraudulent!"
Bought this for my Samsung Galaxy S4 and it is awesome. It is much thinner than the other reviews make it out to be. I was able to put the coil in the back of my phone between the battery and the stock cover (i did not even have to use the adhesive as the pressure between the case and the battery keeps it in place) and you can not even tell it is in there. There is NO bulge in the back of the phone cover whatsoever.
This was the 3rd (and final) receiver I purchased for my S4. The first one was a receiver that looked similar to this one, but was NOT from foneSalesman. the other one was made of copper coils and did not charge my phone. This one works great! Not make of copper coils, but the new printed circuits. NFC works great as well! It doesn't charge as fast as the USB cable plugged straight into power, but I only get these for convenience not for speedy charging.
Really, really wish it worked... but it only works half the time... using it with two separate Qi charging pads, so it's not the pad. The copper contacts on the receiver card just need to be larger... it seems they don't keep contact at all times. I tried putting a small folded piece of paper inside to push the contacts together, but it doesn't work.
The product is exactly as advertised. From my research this is the slimmest Qi Receiver available for the S4 and when installed creates a very small bulge in the back cover. You really have to look to notice it. I use a SGP Neo hybrid case, which fits perfectly fine, and use the Samsung qi charger without any problems.Using the stock battery seems to yield the best results as the 3rd party batteries I have seem a hair thicker.
That's to be expected.I noticed a noticeable bulge when using the OEM back cover. When you lay the phone on a flat surface, it does not lay flat due to the bulge in the middle. Visually, I can't tell. Your case may or may not fit depending on the case.Pros- Thin as you possible can get it.Cons- The USB port may not fit thicker usb cables so well. For example, my blackberry usb cable was tight fit.
Answer: I consider it a circuit that's printed on a thin film of plastic.  The combination is remarkably thin and flexible.  It's not a coil of wire.  It's not a stiff or thick board.