One of Quickboost’s latest products is this set of three 1/48th scale headrests for the F6F Hellcat. Although the recommended kit is Eduard’s, I’m sure this would easily work on Hasegawa’s kit or even the old Arii/Otaki (or even the Monogram if you are feeling adventurous or nostalgic!).
As best I can determine, the middle headrest on this set (with the narrower width) was for use in the -3 (and early -5) Hellcats that carried the small windows aft of the pilot. The other two headrests without this narrower section are identical except for the size of the headrest padding.
The molding is very crisp and in a grey/green colored resin. The accompanying drawing of the set, along with photos on the web, shows that a vertical ‘bar’ should be present on the sides of the pour stub, presumably to offer some protection to the pieces. These bars were missing on my copy, but the headrests themselves were in perfect shape.