In the item description details it says:
"Restrictions -- FFL
Products require a Federal Firearms License to be on file with Brownells. We need just one copy for all future orders. If we don't have a FFL for you, your order will be put on hold until it is received. Please mail a certified copy to Brownells Inc, Attn: Gun Dept, 200 South Front Street, Montezuma, IA 50171."
Under the FAQ section "Basic shipping questions" it says:
"Do I need an FFL license to order an action, frame, or receiver or other product from Brownells?
The majority of our products do not require an FFL. However, you will need an FFL on file with us to buy a firearm receiver, frame, or barreled action, and a very small percentage of our factory parts. These items will be marked with restriction icons.
All sales of firearms are made in strict accordance with all federal regulations. If the item you have selected is marked with an FFL icon you have selected a government-restricted item, and your order will be held until we have the following:
A certified copy of your current FFL license, signed with an original signature in ink. We will keep your copy on file until it expires. At that time, you will need to send in your reissued, signed copy.
Notes about FFLs - There can be no changes or alterations to any information on the copy of the FFL. Your order for the FFL-controlled items can only be shipped to the address on the signed FFL."
At the very top of every web page is the Brownell's phone number where I'm sure you can ask them:
1-800-741-0015