The Felix was a well-armed beastie. A number of photoetched-metal parts detail the weapons. The instructions direct you to use gunsights (Part 5) for all four installations, but the fret only includes two, along with two Part 7 gunsights. The only difference is the length of the post, so they can be easily swapped or modified. The American Felixstowe (decal option C2) requires two Scarff ring mounts, but there's only one set in the kit of brackets. Don't panic: Help is available. According to Richard Alexander at Wingnut Wings:

"Modelers wishing to build USNAS Felixstowe F.2a N4291 (option C2) will require additional Scarff ring brackets and should contact help@wingnutwings.com who will send a small photoetched-metal fret containing these missing parts free of charge."