[Xylakant]

It is fairly common in Germany. There’s a special size of candles that fits those holders (Christbaumkerzen) and they’re a thing you’ll find everywhere in shops around Christmas time. I’ve never had a tree with LED in my entire life.

You must observe some safety rules, have a bucket of water or an extinguisher at hand (not under the tree) and never leave the candles unattended. And yes, be careful where you place the candles. Can’t have a branch that’s hanging over them.