What are regulations for S.I lights used in lifebuoy as per SOLAS ?

S.I  lights shall be such that they cannot be extinguished by water;

• be of white colour and capable of either burning continuously with a luminous intensity of not less than 2 cd in all directions of the upper hemisphere or flashing (discharge flashing) at a rate of not less than 50 flashes and not more than 70 flashes per min with at least the corresponding effective luminous intensity;

• be provided with a source of energy capable of meeting the requirement of previous paragraph for a period of at least 2 hours;

• be capable of withstanding the drop test into the water from the height at which it is stowed above the waterline in the lightest seagoing condition or 30 m, whichever is the greater, without impairing either its operating capability or that of its attached components.