Black mace

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

In-game examine text: "A spiky mace."

It has a Grand Exchange buy limit of 125 every four hours, a high alchemy value of 259 gp, and item ID 1426.

View on OSRS Wiki

Black Mace shows an active flip setup with a margin of +181 gp and 1,000 trades over the last 24 hours.

At the buy limit of 125 every four hours, max profit per cycle is about 22.6k gp — high margin with healthy liquidity.