The boot is more of a dust shield between the shock piston shaft and cylinder housing. There are seals between the shaft & cylinder that will prevent water damage to the working parts. If the boot is available separately, replace it as soon as possible to keep dirt & dust from chafing the seals, which would eventually cause a leak. Before ordereing the boot, visually inspect the shaft for signs of scraping, surface contamination or damage. It should be smooth and shinny. If the shaft is damaged, replace the shock as an assembly.