A slotted‐disk, mechanical velocity selector has been constructed and tested. It is similar to that reported by Hostettler and Bernstein, but may be used at velocities more than five times higher (to 6000 m/sec). Its velocity spread is somewhat less (3.4%), and its fractional open time is about the same (34.8%) as the Hostettler‐Bernstein instrument. A lithium beam has been velocity analyzed and found to be in agreement with the calculated distribution.