I've only used them once, but they worked for at least 3 years (could have been longer, but I moved after 3 years so don't know if the ones I installed are still good)
Just to make sure we're on the same page, the one's I'm talking about had a bolt encased in a 'test tube' - you drill the appropriate size hole, pop in the test tube end and whack the bolt with a hammer to activate/ mix the epoxy - then wait for the epoxy to harden and install the base.
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