My hardware comparison of the Amazon Fire TV Stick 4K gives you an idea of how much Amazon’s streaming sticks have grown over the years. What it doesn’t reveal is how much they’ve changed under their unassuming black plastic housing. I cracked open one of the 4K Firesticks and was surprised to find that it’s nearly covered from head to toe in thick metal heat sinks on both sides. The teardown also gives us a look at the hardware behind the antenna technology that Amazon invented for their new compact media player.

The Fire TV Stick 4K is dead simple to open up without any tools or damage to the housing. Just pry away the housing sides along their seem until 3 plastic clips on each side pull free. Then just slide the top half of the housing up and away.

The first surprise is a thin piece of copper that covers the majority of the top plastic housing. The main metal heat sinks contact this copper sheet through 7 small thermal pads. The 2nd-gen Fire TV Stick had a similar, but much smaller copper sheet, while the 1st-gen Fire TV Stick connected the device’s heat sink directly to the plastic housing with strips of thermal foam.

Bending away the tail end of the plastic housing releases the main board from a pair of plastic clips that hold it in place. Underneath is an NFC tag that is found in nearly all of Amazon’s devices. This is what gets scanned just before Amazon ships out the device so that when it arrives in the hands of customers, it is already associated with their Amazon account, removing the need to log in on the device.

The main Fire TV Stick 4K components are a beast compared to prior Fire TV Stick models. This one has thick metal heat sinks on both sides, whereas older models only had tiny slivers of metal to act as heat sinks on just one side of the device. These beefy heat sinks explain why the Fire TV Stick 4K weights nearly twice as much as the regular Fire TV Stick, even though it is only a little bit longer.

On the tail end of the main board are a pair of antenna “bricks” that facilitate the Fire TV Stick 4K’s superior WiFi capabilities. For comparison, both the 1st and 2nd-gen Fire TV Sticks used nothing more than a series of lines on the circuit board as their antennas. Those devices were quite susceptible to WiFi interference from surrounding electronics.

Marc Whitten, Amazon’s Vice President of Fire TV said “The team invented an entirely new antenna technology and combined that with a powerful 802.11ac Wi-Fi chip that optimizes for the best possible 4K UHD streaming experience, even in congested network environments.” From the looks of those two massive blocks on the end of the Fire TV Stick 4K, it seems like that statement wasn’t just marketing fluff after all. The other side of the blocks is empty, apart from a pair of pads with “ANT” labels, which I presume is short for “Antenna.”

The metal heat sinks are attached very firmly to the processor shields and likely can’t be removed without doing irreparable damage or at least compromising the device’s ability to dissipate heat. Everything snaps back together just as easily as it came apart. First slide the HDMI plug into the bottom plastic housing, click in the tail of the circuit board, then slide the top housing down until all 6 plastic clips click into place.