Eight inserts for Nord Arms Front Sight.
 
Inner diameter of round apertures:
 
A1) 2.0 mm / 0.0787" = 20/254"
 
A2) 2.2 mm / 0.0866" = 22/254"
 
A3) 2.5 mm / 0.0984" = 25/254"
 
A4) 2.7 mm / 0.1063" = 27/254"
 
B1) 3.0 mm / 0.1181" = 30/254"
 
B2) 3.3 mm / 0.1299" = 33/254"
 
B3) 3.6 mm / 0.1417" = 36/254"
 
B4) 4.0 mm / 0.1575" = 40/254"