DMM has issued a critical locking carabiner safety notice and product recall. In certain models of DMM locking carabiners, the interaction between the internal coil spring (which gives the gate its closing action) and the spring pusher (the component that holds the spring against the carabiner body) may cause the spring pusher to displace, potentially preventing the gate from closing or the mechanism from locking completely—thus the gate could open, leading to serious injury or death.
This recall does not affect all DMM carabiners. Visit the product safety warnings and recall notices from DMM for full details in identifying the affected carabiners.
Here are links to the safety warning and product recall posted on the DMM website.
The DMM pdfs are also available to view at the website of the Professional Ropes Course Association, http://www.prcainfo.org/advisories.