Package includes: Packang include 1 piece of trimmer head and 6 pieces of trimmer head replacement blades,a nice combination set for you, saving your time of purchasing blades again Three replaceable thermoplastic blades: can replace the worn blades after long time use,put it on and start working,save your time and labor Compatible with Stihl FS44 FS55 FS56 FS70 FS80 FS83 FS85 FS90 100RX KM55 KM56 KM 85 KM90 KM110 KM130 + FS-KM Compatible with: this trimmer head and replacement blade set is compatible with Stihl 20-3, which doesn't fit for other models; The size of the spiral is 10 x 1.25 cm in length and width, please do check your machine model and check the spiral size before Easy to replace:It's easy to replace the trimmer head blade, just remove the screwdriver of the lawn mower and replace it with a new blade Trimmer Head with 6 Pieces Trimmer Head Replacement Blades Fits For Stihl Polycut 20-3 for Patio, Lawn, Garden . Function: Used for lawn mowing and large area of heavy grass and weeds Applicable: Compatible with Stihl FS44 FS55 FS56 FS70 FS80 FS83 FS85 FS90 100RX KM55 KM56 KM 85 KM90 KM110 KM130 + FS-KM Replace OEM: # 4002 710 2189 Three replaceable thermoplastic blades: can replace the worn blades after long time use,put it on and start working,save your time and labor Trimmer head size: Diameter: 5.2 inches/ 13.3 cm Length: approx. 4.0 inches/ 10.3 cm Hole diameter: 0.5 inches/ 1.2 cm Package includes: 1 x Trimmer head 9 x Trimmer head blades Note: The brands mentioned above and any related model like "Stihl 20-3" are only applied to demonstrate compatibility