Eurorack Hardware Modular Rails are sized to fit most popular case sizes. Most popular are the 84hp & 104hp which fit small cases, 60hp (Mother 32 and others), 70hp (Behringer Model D), and MUCH larger. These rails pair nicely with Eurorack Hardware’s DIY Case Brackets or Bracket Ears. Also choose 3mm slide nuts or nut strips for module mounting. Made of hardened industrial aluminum, guaranteed to be tough. Sold in pairs and includes rail end mounting screws.