StewMac's R&D team designed two standard models, for acoustic guitars with Martin Dreadnought and post-1955 Gibson® J-45® shapes. The Repair Guard slides right into place—no need to remove the strings.
Why do you want it?
Protect against accidents! A quick slip of your bridge reamer or slotting saw, and you'll have a dinged finish to repair, or worse.
Unlike a bare soundboard, the Repair Guard can take a bit of weight. A couple of tools resting on the guard can save you a long reach to your bench.
For light duty work, you can clamp right on the guard without leaving a footprint in spruce like a caul might.
You can scribe brace patterns on the guard for different guitars, a great help for locating brace locations for repairs.
A Repair Guard can slide into place with the strings still on!
In some cases, you may need to modify your guard—to fit an oversized bridge, for example. Use a medium file to change the shape, and a fine file to smooth the edges. Support the guard directly under the edge you're filing by hanging it off a clean flat table. To avoid fracturing the plastic, don't let it chatter up and down as you file.