Medium can fit:

• 1 BIO and 3 smaller lenses
• Up to 5 or 6 smaller lenses
• 2 BIO lenses
  

Medium cannot fit:

• Gonio with Handle
• Super Macula 2.2
• Macula Plus 5.5
• Blumenthal Suturelysis

Large can fit: 

• 2 BIO and 3 smaller lenses
• 1 BIO, 1 Scleral Depressor and 4 smaller lenses
• 1 BIO, 1 Gonio with Handle and 3 smaller lenses
• 1 BIO, 1 Gonio with Handle and 1 or 2 smaller lenses 

The case is designed specifically for Volk lenses, so we can't confirm that other brands will fit properly.