Adjustable Straight Edge RWS111 These tools are great for carpet fitters who do lots of stair nosings,

Using this tool you are able to get very accurate measurements and are able to transfer them to nosings for cutting on site or making a list for later. This tool has two sliding  aluminum surfaces which are locked by a finger tightening nut. It can be adjusted between 60cm to 100cm. This tool is great for working in door ways and on landings.

When being professional counts this is a tool you should have.