Outer edge to outer edge 13-3/4". Inside surface of magnetic stripe holder is 10-3/4". Real magnets measuring 9-7/8" end to end. I purchased this item (four magnetic stripe tool holders included) to fit a long, thin, perforated board. Mounting holes do not match the pad. The two extreme holes fit on a perforated plate, but they are angled. They don't claim to fit on a perforated plate, so I'm wrong if I assumed! up to hold them together so I'm asking which part of this item is 12". Wouldn't recommend. Such a shame great Magnet d Harbor Freight tool holders are too long for my project.
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