The F1 grenade has been in use since 1915. Up to 1935, the grenade was fitted with a lot of different fuzes.
Most fuzes were developed during ww1. Patrick Delhomme describes a lot of them in his book.
Grenades carried a wooden plug during transport, with separately packed fuzes.
Filling in 1915-1916 was 60gram Cheddite or Schneiderite.