Speedometer theft protection

My daughter new bike is equipped with a speedometer, but it's not that easy for her to keep in mind to remove it when parking her bike at the playschool...

To prevent many tears when it would be stolen, we installed a little anti theft protection. A two piece border is attached around the small computer so no turnig to remove it from it's holder is possible. So there should be no theft by walking by and getting it off. To remove it you have to climb the fence and use a tool. This should be safe enough für a 9€ speedometer.