I am trying to find a way describe a product feature, this would be that once the product is mounted, it cannot be easily un-mounted by shock, movement.
The expression in German Hält Bombenfest which approximately means bomb proof, describes it very well, please not that I am not looking for a translation of this, rather a natural way of saying it in English.
My first intuation was shockproof, but I don't feel this accurately describes it, since I think more of a camera falling down.
The closest I've found so far is something like securely fastened, since fastened describes the holding pretty well though I'm still not satisfied.
Just in case it's relevant, the product itself is a silicone mount that holds a smartphone to a bike's handlebar.