Read from the World of Warcraft client build files.
How Nightstalker's Trousers Compares
Who It Suits
Leather is the armor type Demon Hunter, Druid, Monk and Rogue wear. With Agility or Intellect, Nightstalker's Trousers suits Assassination, Outlaw and Subtlety Rogue; Brewmaster, Mistweaver and Windwalker Monk; Balance, Feral, Guardian and Restoration Druid; Havoc, Vengeance and Devourer Demon Hunter.
Similar Items
The 10 items nearest to Nightstalker's Trousers (item level 13) in item level among Armor > Leather, Legs slot, from item level 8 to 18.
Blizzard numbers items as they are created, so the named items next to ID 240326 (240321 to 240331) were usually added in the same batch as Nightstalker's Trousers: the same quest line, zone, vendor or reward set.