With the Platinum Drywall Tools Corner Roller with Extendable Handle you can roll out your internal 90 degree corners with ease. Immediately after applying the mud and tape into the corner, you will use this tool by rolling it over the tape. This process forces the excess joint compound out from under the tape and properly beds the corner. It creates a nice sharp corner. The extendable handle extends from 45-70". Use a corner flusher or angle head after using this roller to clean up the excess compound. (sold separately) If you are going to buy one drywall taping tool this is it. This tool will greatly speed up your drywall finishing.