Not strong, but i've got this one and it does what you want it to.
https://www.trade-point.co.uk/departments/bosch-truvo-multi-detector/1518921_TP.prd?gclid=Cj0KCQiA8vSOBhCkARIsAGdp6RRMbWsFVc7ZCPmo2jik5hZVDsnHdLe1peg_kIMUNDEzPHONOZHZEBQaAt82EALw_wcB&gclsrc=aw.ds
Cheers - was looking at that one. There are also quite a lot on Amazon that claim to tell you the material, centre point, etc.. But I don't really trust Amazon...
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Not strong, but i've got this one and it does what you want it to.
https://www.trade-point.co.uk/departments/bosch-truvo-multi-detector/1518921_TP.prd?gclid=Cj0KCQiA8vSOBhCkARIsAGdp6RRMbWsFVc7ZCPmo2jik5hZVDsnHdLe1peg_kIMUNDEzPHONOZHZEBQaAt82EALw_wcB&gclsrc=aw.ds