The adapter you need for your SSP18 for the Open Universal Holster.

Might be compatible with other Glock models but we cannot guarantee it.

Mount: Picatinny

 This is not a heavy-duty holster solution. For heavy use, please stick to our full enclosure polymer holsters. Be aware that this mount attaches to your pistol’s frame only. If you apply a major force onto your pistol, while it is in the holster, by falling on it, or putting your entire body weight onto it, the pistol or the metal adapter can get damaged.