Strike Planet gives us an overview of the PyroFX RGD-5 (D) White Chalk pyro grenade... "Authentic replica of the RGD-5 airsoft grenade. The body of the grenade and the initiation mechanism are made of plastic, so you can not be afraid of traumatic fragments.
Marty Airsoft reviews the TAG-19 pyro grenade for airsoft use made by TAG Innovations/Airsoft Pyrotechnics. If there is an uncanny resemblace to a real world grenade, it is because it is based on the RGD-5, the fragmentation grenade developed by the Soviet Union in 1950s and it is still in use by many countries who were in the Soviet Union's orbit during the Cold War.