These bags only hold items obtained in the mining profession, but are usually larger than the average world drop or craftable bag. Only 1 mining bag may fill a slot in a bank at any time.
“Mining bags are special bags first made available in World of Warcraft: The Burning Crusade...Mining bag
“This item can be purchased for 10 from: Wuark <Armorer& Shieldcrafter> in Razor Hill, Durotar...Mining Sack
“Mammoth Mining BagItem Level 75Disenchants into: Not disenchantableBinds when equipped32 Slot...Mammoth Mining Bag
“This item is created with Leatherworking (500): [Pattern: Triple-Reinforced Mining Bag]. Patch...Triple-Reinforced Mining Bag
“Reinforced Mining BagItem Level 65Disenchants into: Not disenchantableBinds when equipped28 Slot...Reinforced Mining Bag