The curtain that FR supplies is just a large, usually tan, piece of hemmed cloth. It will be around six foot across and three to four feet high depending on your model. One long edge will have female Velcro sewn on to connect to the Velcro dots FR installs along the cab front.
I use other covers along with the FR privacy curtain. Adco makes the a nice white vinyl external cover that covers the windshield and side windows. I also use it when I'm storing our RV to keep the sun off the dash and out of the coach. The part is SKU:
256410074. You can see a picture of it Here
High End Motorsports sells a nice set of internal reflective covers you can see Here
I've used both products and both are well made, quality products.