Material: Plastic, Length: 67mm Good for grass and thin brush, not for young trees or other hard materials. For best performance, avoid using this attachment for edging, working with bricks, chains or Suitable for RYOBI RAC155 RAC157 String Trimmer 【ABOUT REPLACEMENT BLADES】 Made of PA6 (Nylon), put the blades in water overnight before use, they will last longer. Quantity: : 50 Replacement blades for RAC158, perfect replacement blades for the original blades. Product dimensions (L x W x H) ‎13 x 8 x 4.5 cm; 82 grams Reference ‎GCJ-013 Color ‎50 Blades