These are light and easy to use. All that is needed is to take it out of the storage box, hook it around the window ledge and drop the ladder out of the window, just like a rope ladder. 7.5 metres (25') is good for second floor use.
This ladder will fit a window opening (width) of up to 325mm with a wall thickness of up to 250mm. There are stand-offs to hold the steps off the wall and these are loose in the box. This style of fire escape ladder is not recommended for Dormer windows.