The WirelessHD Kit is more for the “cord cutters” among us – those who do not desire cables strewn about everywhere. Since the K138ST is a short throw, it will likely sit in front of your seating area, making it an awkward position for your gaming systems and Blu-ray players. With the WirelessHD Kit, you can place those devices anywhere you want in the room with no regard for where the projector lives. Nice. It comes with a transmitter that connects to your image source via HDMI, and a receiver to plug into your HDMI port on the projector. The signal is wirelessly transmitted between the two devices. The WirelessHD Kit is capable of transmitting video and audio from a computer with an HDMI port.
So, it really comes down to this – will you be using the wireless capability of the Acer K138ST to project videos and such from your phone or tablet, or just the computer? If so, go with the roughly $200 WirelessCAST dongle. If you’re just trying to wirelessly project from a gaming or Blu-ray device, or from a computer, go with the $199 WirelessHD Kit. I had a maddeningly difficult time finding that WirelessCAST dongle though – it doesn’t appear to be on the Acer store website, nor could I find it in any online store that wasn’t dealing in South African Rand. I found it on Amazon for $220 plus $35 shipping, and on a UK site for £68.71, which works out to about $92 plus 20% VAT and an £8.99 ($12) shipping fee. By comparison, the WirelessHD Kit is beyond easy to find. It’s everywhere. So weird.
Naturally, I did not have the Acer WirelessCAST to test (who does?), but I did have the WirelessHD Kit from when I reviewed the Acer H7550ST, a $999 DLP projector. It worked just as well with the K138ST. Once inserted into the HDMI port on the projector’s back panel, the HDMI option is replaced with the “WirelessHD” option within its source menu. The kit comes with a User Manual to make the process quick and easy. My PlayStation 4 is pretty much installed on the shelf behind the couch, hooked up to my Epson HC5040UB via a 4K splitter, and is a total pain to move to test these short throw projectors, so I rather appreciated the placement flexibility offered by the WirelessHD Kit.