- Barrel Diameter: 1 1/2", Bristle Diameter: 2 3/4". Healthy Hair by Olivia Garden is a collection of eco-friendly brushes made from bamboo.These are Professional Brush Made from Bamboo that is stronger, lighter and more durable than wood. Bamboo is a 100% natural renewable resource. Using bamboo preserves hardwood forests. 100% Natural Boar Bristles are gentle on hair and scalp, grant superior styling results, and are ideal for straightening hair. Boar bristles distribute hair’s natural oils for a smooth and shiny finish. Ergonomic Handle makes the brush anti-bacterial, lightweight, and anti-slip with its sure grip handle. Healthy Hair brushes go great with matching Healthy Hair combs!