Last one! This is an airgun barrel harmonic tuner, a concept similar to the Browning BOSS. These were hard to get when I acquired some back in 2002. Sold three out of four at this price point. Decided to keep the last one, but then decided I'll never use it. Fits .177 - .25 barrels. New, old stock. Still sealed. No trades, third party, or international sales. Will ship in a USPS small rate box insured for $8.10 CONUS. Buyer pays shipping charges. Paypal FF/Good and Services (+3.3%)/Venmo. Asking $90 + shipping.