Figure 28. RAF split lens laminated ‘windows’. Centre, First Mk IV ‘windows’; separate pieces of laminated glass. Left, Mk IVa & IVb, glass is sitting on a brass sheet frame and held by small bent tabs, less fiddly than separate pieces, but still weak and easily flattened or broken when not in the main frames. Right, Mk VII & Mk VIII, the glass is now held in a ‘U’ section piece of brass channel, these could withstand rough storage and repeated changes. Back ground L-R; US AN6530; Luftwaffe 295; Japanese ’Eagle Eye’.