There are two kinds of slide locks used in Shadow Systems pistols. See photo for how to identify them.
Leaf Spring Slide Lock: This style is currently used in MR pistols and has been used in DR/XR models in the past. This style also works with Gen3 and Gen4 style frames.
Coil Spring Slide Lock: This style is currently used in DR/XR models. This style also works with Gen5 style frames.
Restrictions: By buying this item from Shadow Systems, the Customer certifies that the Customer will comply with any and all requirements imposed by applicable U.S. federal, state, and local laws, regulations, and administrative policies.