Reliable.

We've taken down all the decorations and put them away, but always check the tree lights, before packing them, because it's easier than finding out that you have a problem next Christmas.
  These old faithfuls belonged to J's Mum and are over forty years old.
They never fail to light up, every year.
 We also have a pack of Woolworths spare bulbs !
If you're into Health and Safety, you didn't read this !