Provides Traction: When the lawn is wet or the ground has many inclines and slopes, the nails give the robotic lawnmower better traction, eliminating the need to dig in the lawn Built to Last: Made of high-quality plastic material, wear-resistant and durable, and the right size to provide you with long-term service Easy To Install: Just center the spike on the wheel and secure it with the included screws Beautiful Lawn: High-quality spikes ensure a beautiful lawn. No more holes in your lawn with your lawn mower robot Compatible with: Husqvarna Automower 330 Husqvarna Automower 440 Husqvarna Automower 420 Husqvarna Automower 435X AWD Husqvarna Automower 430X Husqvarna Automower 435X Husqvarna Automower 450X Husqvarna Automower 450X Package included: 2 x Spikes 21 x Self-tapping Screws 1 x English User Manual Other things not included