Silica gel packets need to be used with an air-tight sealed container, but they do not need to be vacuum sealed.  Also, you can open the jars or containers that you have stored your food in with silica gel packets.  They are moisture absorbers.  If you have rice, beans, cereal, chips, herbs, spices, or any dry food in your pantry that you use periodically and want to keep them dry, silica gel packets will be your choice.  Also, silica gel packets are reusable.  Meaning, when they are saturated with moisture, you can easily dry them out in a microwave or oven.   If you want to store away food for a long time (more than a year) and you won't open them at all, oxygen absorbers are your choice.  Also, you will need to use thick mylar bags or mason jar to store your food. Oxygen absorbers are not reusable.  As 21% of air is oxygen, it's not good to open your bag of food with oxygen absorbers as oxygen will be reintroduced to your stored food. You may read on the internet that states not to use oxygen absorbers and silica gel packets together.  There are certain types of oxygen absorbers that require moisture to activate them. With that type, it's not recommended to use silica gel packets as they will absorb moisture and your oxygen absorbers won't work. However, all of our oxygen absorbers that we sell on our website are self reactive types that do not require moisture. You can use both our food safe silica gel packets and our oxygen absorbers together for your long-term food storage. This way, you are protecting your food from moisture and oxygen.  There are many commercial snack companies using both silica gel and oxygen absorbers together.