SL676 T-Square is what you need.
T-Square,Aluminum,48in. The Sands Level & Tool Co T Square is an ideal addition to your toolbox if you are working on drywall, wallboard or other boards that need measuring and spacing.If you are looking for a tool that can help you with drywall, wallboard and other boards that need measuring and spacing, the Sands Level & Tool Co. The 16 in arm gives you greater reach while doing your job.