Most injection pen storage cases make you choose between storing what you have now and planning for what you'll have later. The MC Stack doesn't make you choose. This is a low-profile, flat-laying fridge storage case designed to hold 4 Zepbound, Mounjaro, or Trulicity auto-injector pens - and stack cleanly with additional MC Stack 4 units as your supply grows. Each case has four precision-fit corner posts on top and four corresponding receptacles on the bottom, so stacked units lock into place and stay exactly where you put them. No sliding, no leaning, no reorganizing every time you open the fridge. The 3D-scanned internal saddle system - built from an actual scan of the Zepbound and Mounjaro auto-injector geometry - cradles each pen precisely. The low-profile design lies flat on your fridge shelf and takes up only as much vertical space as the pens themselves. Stack one for a single month, two for two months, or four for a full four-month supply. Buy what you need now and add more later - every MC Stack 4 is compatible with every other MC Stack 4. Note: MC Stack 4 units are only compatible with other MC Stack 4 units. They are not cross-compatible with the MC Stack 5. This is a fridge storage case. It is not insulated and not designed for travel. If you need something travel-capable, check out the MC Cannon or the MC Solo. Made from rigid plant-based bioplastic. Designed, printed, and shipped from Michigan. Compatible with: Zepbound, Mounjaro, and Trulicity auto-injector pens Available in: 1, 2, 3, or 4 stacked units - choose your quantity at checkout Features: Holds 4 injection pens per unit Interlocking corner post system - stacks securely with other MC Stack 4 units Exclusive 3D-scanned internal saddle system for precision fit Low-profile flat design maximizes fridge shelf space Modular - add more units as your supply grows Made from rigid plant-based bioplastic Multiple color options, custom colors available Designed, printed, and shipped from Michigan Important: Case only - pens not included Not insulated, not a cooler - fridge storage only Only compatible with other MC Stack 4 units - not cross-compatible with MC Stack 5 Hand wash with cool water only Per Eli Lilly's prescribing information, Zepbound single-dose pens can only be stored at room temperature for up to 21 days and cannot be returned to the fridge once removed Aftermarket storage accessory - not affiliated with, endorsed by, or sponsored by Eli Lilly, Boehringer Ingelheim, or any pharmaceutical brand. Always follow your healthcare provider's instructions and the manufacturer's storage guidelines for your medication.