Starfleet-issue jet boots are used to propel an individual to heights that he or she would normally have to reach by climbing or using bulky equipment. The boots are of a fairly standard size, with the booster (or perhaps thruster) in the heel of the boot and most likely propellant fore of the booster. One conclusion of the jet boots method of propulsion is similar to the thrusters used on a starship. Jet boots are modeled to propel only a certain weight (presumably around 600 pounds, or three human men) but may be designed for use of heavier officers and species. Furthermore, jet boots are capable of firing the "rockets" which expands a great amount of fuel in a short amount of time, resulting in a very accelerated speed.
In Star Trek V: The Final Frontier, Spock first used the jet boots to observe Captain Kirk while making his ascent on El Capitan. The second time they are used is when Kirk, McCoy and Spock attempt to climb a turboshaft whilst being pursued by Sybok and his followers on the Enterprise-A. (Star Trek V: The Final Frontier)