Our Citronella Smelters' citronella oil is obtained from the leaves and stems of various types of Cymbopogon (lemongrass). Citronella oil has a powerful citrus aroma, bursting with a fresh, lemon and grassy scent. Method of use: - Place one Easy Block Smelters in a burner (depending on the size of the burner) - Light a tea light (approximately 4 hours) and put it in the burner - Let the scent spread into the room Smelters last 2 to 3 tea lights. Each bag contains 10 pieces Strengths: We choose to produce Smelters in 2 strengths (mild and strong). Aware! Because not every space is the same size and each person has a different need. It is therefore highly recommended to include both strengths in your range.