Do I need the Fresh & Save pump to use these jars?

Yes for the vacuum feature. The jars close with their lids, but the air-removal seal requires the Zwilling vacuum pump, which is not in this set.

Can these jars go in the freezer and microwave?

The plastic bodies are suited to fridge and pantry storage. Check the lid and body markings before freezing or microwaving, and avoid microwaving with the lid sealed.

How does this compare with glass containers?

Plastic is lighter and less likely to shatter, but glass resists scratches and stains better. The vacuum seal is the main advantage over ordinary glass clip-lid boxes.

Are the jars dishwasher safe?

Yes, the jars and lids are dishwasher safe. Place lids so they do not warp, and hand-dry the seal area if you want the best grip.

What sizes are in the 12-pack?

The set mixes small, medium and large square jars for spices, leftovers and bulk dry goods. Check the listed sizes against your shelf depth before buying.