Made for: FOR ABC-M17, M17A1, AND M17A2 FIELD PROTECTIVE MASKS. NSN# 4240011040965. These are unused and measure 7/8" diameter. We have seen these selling online for $6.00/pair. Price is for 2. 10 or more sets of 2 the price drops down to $0.75 per set and 50 or more sets of two the price drops to $0.50 per set.