You are purchasing a 12-count  lot of O Scale ladders fabricated by Todd Architectural Models & Layouts.  The ladders are 2" tall which is 8'-0" in O Scale.
 
The stock number is O-LADDER1.

Assembly is easy! 
1. Curvature of the peice is due to the heat during the laser cutting process. Carefully bend th eladder in the oposite direction to remove the curvature.
2. An extension ladder may be easliy created by removing a portion of release paper on the back of one of the ladders abd sticking it on the front of another.
3. Use Krylon Matte or Dull Aluminum spray paint for a metal color.