Holsters have different retention levels. You'll see Lvl I, II, III and even IV. The level of the holster relates to how many actions a user must make to release the gun from the holster. Friction is Lvl 1, Friction + Strap is Lvl 2. Friction + Strap + Lever or button would be lvl 3, and so on. Most people use at least a Lvl 2 retention holster, so someone just grabbing and pulling isn't going to release the gun. Most Law Enforcement use a Lvl III holster.