Klank's gauntlets are obtained during the quest Underground Pass, where they are used for searching the Half-soulless' cages. In the early stages of RuneScape 2, these gloves were very commonly seen on high levelled players, but since have lost popularity to be worn as there are much better choices, such as the gloves of Recipe for Disaster.
If lost they can be re-obtained from Klank for a price of 5,000 coins. The easiest way to reach Klank is to teleport to the death altar using a wicked hood and enter the tunnel there to reach Klank. Some may find it useful to buy multiple pairs in case they are lost. The drop trick is not needed to purchase multiple pairs.