Here is what the manufacturer says about them:

In compliance with BS EN 60598-01, BS EN 60598-2:20

Rubber festoon cable must be used for all permanent outdoor installations in accordance with BS EN 60598-1

Max lamp rating 25 watts.

Tough H05RNH-F cable for outdoor use (Its flat).

All rubber festoons are fitted with a 2P+E BS60309 IP44 rated plug

The high temperature rating of the lampholder rubber seal ensures a long life seal directly onto the golfball or GLS lamp.

All harnesses have electrical insulation rating Class II (double insulated)

Weatherproof rating IP44 when lamps fitted.