The L68a1(green), L69a1(orange), L70a1(red) and L71A1(blue) are coloured smoke grenades used by the British forces.
On the photos below you see the types I have in my collection, I'm think still missing some colours.

Total length : 140mm
Length w/o fuze : 120mm
Diameter : 64mm
Weight : ? gram
Filling :
smoke compound


Grenade taken to bits in steps :