Officer safety is critical. That’s why Safariland created the Retention Level system as a guide to holster selection.
Retention levels are tested with the initiation of a “grab and snatch” by an adversary. To qualify as Level 1 Retention, a holster must provide for unlimited direction of force for five full seconds. At the end of the five seconds, the weapon must still be secure in the holster and the holster must still be attached to the wearer. The wearer must be able to accomplish a draw after the attack.
These tests are then repeated with additional safety measures (with previous safety measure disengaged) to determine where a holster falls on the retention spectrum. This video demonstrates the operation of various Safariland retention holsters.