Steel longsword

Steel Longsword is a free-to-play item on the OSRS Grand Exchange in the weapons category.

In-game examine text: "A razor sharp longsword."

It has a Grand Exchange buy limit of 125 every four hours, a high alchemy value of 300 gp, and item ID 1295.

View on OSRS Wiki

Steel Longsword shows an active flip setup with a margin of +63 gp and 2,196 trades over the last 24 hours.

At the buy limit of 125 every four hours, max profit per cycle is about 7.9k gp — high margin with healthy liquidity.