The handrail provides a handhold for passengers while they are riding the escalator. The horizontal valve was still tucked under the handhold, operated by the right thumb. The handhold is lubricated and the spindle is carved to about thumb thickness, usually long. Additional downward pressure is generated by the handhold. The bearing block (handhold) can be made of anything that is harder than the spindle. A second handhold pole in the door areas was introduced with the A2.2 series trains. Experts believe the leak was caused by astronauts using the hose as a handhold. During these turns they may twist and tie their handhold into intricate pretzels. It is danced with various types of single and double handhold. In some dances the connection is loose and called dance handhold. Another problem was that the magazine was also sometimes misused as a handhold.