You know what its like - you move to a small Californian town in the mid 80's and you mysteriously can't find a couple of tools that you are sure you packed...
You need The Lost Tools kit.
I tend to find that two tools in particular always go for a walkabout in the workshop. That's the 10mm socket and 13mm spanner. It's probably because they get used more that most other sizes ... or there could be something strange going on.
I know I'm not alone and have seen those two empty slots in many a tool box.
This little kit either fills those holes, or gives you spares for when they do go missing.
Both made in the UK by King Dick tools. You receive;