Someone on another forum asked about how these were used. I recall there was a time when the person asking that question could've been me. So, although familiar to many of us, here's the shop made right angle clamping aid for any who have missed it or thought it not useful.
Attachment 38137Attachment 38138
Came in handy building my router table.
P.s. A well tuned TS sled makes them easy to knock out. Mine are 7-1/2" and 10-1/2" on the long sides. Most plans I see are 12" on the long sides but I don't do many cases that large and find these sizes convenient.