Proboscis

The Proboscis is a members-only Old School RuneScape item — “A giant mosquito's proboscis, aerodynamic and sharp!”. Its Grand Exchange buy limit is 100 per 4 hours. Right now it buys at 650 gp and sells at 1,400 gp — a net margin of 722 gp (111.1% ROI) after the 2% Grand Exchange tax of 28 gp. High alchemy yields 3 gp.

To flip it, place a buy offer near 650 gp and a sell offer near 1,400 gp; the spread minus GE tax is your profit. Confidence figures are model estimates from live OSRS Wiki prices, not guarantees — flip responsibly.