Just in case you didn't figure it out. That's a "sub leading edge", Ritch Uravitch uses it on his designs, the P-51 and T-6 Texan anyhow. It's a little different, but you glue it to the front of the ribs then the leading edge, then the sheeting just butts to the leading edge instead of overlapping it like most other kits, and the sub leading edge gives more area to glue to, and keeps the sheeting from sagging. It should be 1/8" smaller than the leading edge(roughly) so you have 1/16" top and bottom for the sheeting. I hope this helps.