Petzl Ascension Hand Ascender
This ascender locks in one direction and can be pushed, nearly friction free, in the other. It attaches midline on ropes measuring 8 to 13 mm (5/16 to 1/2 in. dia.) and have a spring-loaded safety latch that must be manually tripped to insert or remove rope. Right hand Ascender, Gold, by Petzl.