The Small (4 gram) Boveda pack measures 2.5″ tall x 2.75″ wide. Put a Boveda Humidipak in your air tight container and relative humidity will be controlled at the RH level printed on the pack. Perfect humidity is essential for keeping smoking material fresh for any length of time. This makes a great gift for all the cigar and medicinal herb fans in your life. Boveda’s 2-way humidity control is the only technology that can be pre-formulated to a specific humidity level with an accuracy of +/-2%. Boveda guarantees a constant level of humidity that never fluctuates or cycles. It also eliminates the conditions that allow for the growth of bacteria, mold or mildew. You will never have to use distilled water sponges, tortilla, bread, lettuce for re-hydration of your herbs and cigars.