Ava's alerter

Ava's alerter is an upgraded version of Ava's accumulator that can be obtained during the Do No Evil quest. Since it requires part-completion of the quest Do No Evil, the minimum Ranged level needed to wear this item is 50. It offers ranged attack and magic defence bonuses which are one point higher than those of the accumulator. In the quest, the player takes a metal box to Ava in order to get a device that can detect buried metal items. She then takes your accumulator and adapts it to search for exact same metal boxes.

Just like the accumulator and attractor, Ava's alerter doesn't work while wearing a metal body.

If the alerter is lost it can be re-obtained by Ava using the 'Buy Device' option and selecting the Alerter. This will get players a new Alerter (for 999 coins and 75 steel arrows).

Elite Clue Scroll
The alerter is capable of detecting crates containing elite clue scrolls. There are four possible locations where elite clue scrolls can be found. Each player can find a scroll in one of four locations.

Requirements: Completed Do No Evil, Ava's Alerter (equipped without metal armour in the chest slot), Spade

If your alerter fails to detect anything, move onto the next location. The coordinates in each location appear to be the same for each player.

There is confirmed on the Free Elite Scroll thread, that there are other places where they could be found.

These have yet to be discovered, so if you find one, add it here.

Attracted items
The alerter works with:
 * Arrows (Holds up to rune both normal and brutal, but some dragon arrows will still be left on the ground.)
 * Crossbow bolts (Includes bone bolts, kebbit bolts, and broad-tipped bolts. When fired some are still left on the ground. It will not work with black bolts, although this may simply be a glitch.)
 * Darts
 * Javelins
 * Throwing axes
 * Throwing knives
 * Toktz-xil-ul (Obsidian rings)

Other items that the alerter can occasionally attract and deposit in the inventory (or the ammunition slot if the player has that item or no item in the slot) include: Note: Cannon ball are not attracted/created.
 * Steel arrows (common)
 * Steel bars
 * Iron ore
 * Steel nails
 * Steel med helms
 * Toy Mouse

Trivia

 * The examine of "...ready to serve and detect." is a pun on the U.S. police motto "Ready to Serve and Protect"