Ring Boomerang

Ring Boomerang (リングブーメラン) is Ring Man's special weapon. It has a somewhat limited range and, as its name implies, boomerangs back. But it can do multiple hits if aimed correctly. The Ring Boomerang can also pierce Skull Man's Skull Barrier, causing normal damage to the robot even when he's shielded. In Mega Man IV, the Ring Boomerang can take items and pull them to Mega Man.

The Ring Boomerang is also used by the "Bridge" in Mega Man IV and the Weapons Archive in Mega Man 10.

Capacity
One Ring Boomerang uses 1 weapon energy unit in Mega Man 4, and 2 Ring Boomerangs use 1 unit in Mega Man IV. With a full weapon energy gauge, Mega Man can use Ring Boomerang 28 times in Mega Man 4 and 38 times in Mega Man IV.

Bosses weak against Ring Boomerang

 * Mega Man 4: Dust Man, Mothraya, Tako Trash and Wily Machine No. 4 (1st form)
 * Mega Man IV: Toad Man

Other media
Mega Man uses the Ring Boomerang in the Mega Man cartoon.