Used in indoor and outdoor climbing for anchors and hanging quick-draws. They are also a great item for installing hanging training tools like the Power Balls.
Never install bolt hangers into t-nuts for anchor setups (top-rope anchor or otherwise), or for quickdraw attachment points. For this style of application is it critical that the anchors are installed directly into structural supports that can support the necessary loads. When using bolt hangers as a life safety device you MUST be confident in the installation and/or consult a structural engineer.