These are special sized washers that are designed for 5mm pivots. The I.D. is 5.05mm. These are very rare!!
Specifications
PBW5MMA = .300 OD X .200 ID X .O22 THICK
Note: (1 set = 2 washers)
(*These will fit most common import balisong butterfly knives with 5mm pivots. Most require 4 total washers for replacement.)