This Japanese manufactured rear sight assembly is for the Type 99 Arisaka bolt action rifle in 7.7 caliber and is in good condition exhibiting a mixture of thinning original blue finish with a brown patina and having some spots of rust. The rear sight slide has the option for the aircraft arms but they are not present. The rear sight spring screw and mounting screw are missing.  (file photo)

Note: Japanese Type 99 Arisaka bolt action rifles with the following arsenals and / or serial numbers have been observed with this part: 16866 & 21908