An expression for very tightly secured/mounted/fastened

Question

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.

Answer 1

You might say the device anchors the phone, or holds it fast (“firmly or securely fixed in place; stable”).

Answer 2

In terms of a product, I do not see much wrong with securely mounted - having said that you may prefer to use something like steadfast, steady or solid. For a more human aspect you could use the word dependable.

We do use the phrase "bomb proof" in English quite frequently but this usually refers to reliability of a product.

Answer 3

You can also go the way of "unmoveable once mounted".

(I was going to add "vibration-proof" as another option but that would also imply the phone won't get damaged if you ride the bike over very rough terrain, which is not your claim.)