They are some members of H&K MP5 Club in STT Telkom Airsoftgun : Lovers – Tactics – Hobby (ST3ALTH). From left to right : Anaka, Fatmonkey, and Dimmy_Nasgor. The picture was taken by myself. I own 1 H&K MP5 Sub-machine gun replica, so I am member of MP5 Club too.
A little brief history of Real Steel H&K MP5 taken from Wikipedia :
The MP5 is a 9 mm submachine gun of German design, developed in the 1960s by a group of engineers from the West German arms manufacturer Heckler & Koch GmbH (HK). The company, motivated by the success of the G3 rifle developed a group of small arms consisting of four types of firearms (all based on the G3 design layout), where the first type was chambered in 7.62x51mm NATO, the second – using the 7.62x39mm M43 round, third – the intermediate 5.56x45mm NATO caliber and the fourth type – chambering the 9x19mm Parabellum pistol cartridge. The MP5 (short for Maschinenpistole 5) was created within the fourth group of firearms, initially known as the HK54.
Work on the MP5 began in 1964 and scarcely two years later it was adopted by the German Federal Police and army special forces. It is currently used by the armed forces and law enforcement units of over 40 different countries. The submachine guns are manufactured under license in several countries including: Greece (Hellenic Arms Industry), Iran (Defense Industries Organization), Mexico, Pakistan (Pakistan Ordnance Factories), Sudan (Military Industry Corporation), Turkey (MKE) and the United Kingdom (initially at Royal Ordnance, later diverted to Heckler & Koch Great Britain).
In this picture, those are MP5 Japan Version with “j” retractable stock. My MP5 is Integrated suppressor (Schalldämpfer) version with “j” retracable stock too but sometimes I change the stock with fixed stock