OO/4mm/1:76LX146-OO MIDLAND RAILWAY SIGNAL BOX WINDOWS PACK OF 20 Laser Cut Self-Assembly Kit For OO Scale Model Railway LayoutsA pack of 20 assorted sized Midland Railway signal box window frames (unglazed). Ideal for use when scratchbuilding signal boxes & other period buildings. Manufactured from 0.8mm laserboard for excellent scale realism. The larger windows are assembled from two layers of board giving the appearance of sliding / opening windows.