Lower Unit Locks By Panther Security Systems Is your boat engine lower unit safe from theft? Don't be fooled, a thief can steal your lower unit in minutes. Protect yourself with The Panther Security Systems' New Tamper Resistant Lower Unit Lock Kits. These tamper resistant bolts and nuts replace your existing lower unit bolt(s) and nut. Both require the unique Tamper Resistant Tool to install and remove. Each with a unique pin configuration to deter even a professional thief. The high strength Bell Washer protects against utilizing any other clamping device to remove the Bolt and/or Nut, deterring the boldest of thieves. Constructed of marine grade Stainless Steel for strength and corrosion resistance.