Great, cheap: the top

Really great and much cheaper than what I could find at competitors (often in ornate terracotta stuff that cost a blind).
I bought 8 lots 4 on another site that Amazon and I paid a bit more expensive ...
Here at 1.83 euros for 4 with free shipping, I do not think you'll find better (indeed, I will re-order).

The principle is simple:
1 / Drill these sprinklers on several locations (with a drill or punch is perfect)
2 / Screw a full bottle of water
3 / Push the open ground in peak right next to the plant you wish to moisturize.
4 / When the bottle is empty, unscrew the filling, screw the tip, etc.

Just a clarification: the screw cap is not suitable for all plastic bottles ... It does not fit the type of bottles Volvic, Evian or Crystalline. You will have screwed Salvetat type Badoit bottles that have no narrower screws.