Microwave popcorn became popular in the 1980s and was the first use of microwave oven technology in the 1940s. In many cases, popcorn made in a microwave ends up not fully popped, leaving unpopped kernels in the bag. In 2008, National Presto Industries introduced a device used in microwaves that is meant to obtain a higher yield of popped kernels than a microwave bag.
Presto developed the PowerPop microwave multi-popper for people who wanted to make popcorn in their microwaves without using pre-packaged products, which may contain unwanted oils or other chemicals. The multi-popper consists of the permanent PowerBase Concentrator, the replaceable PowerCup Concentrator, and a combination popping and serving bowl.
The PowerCup Concentrator is a plate-like insert that you place in the multi-popper to increase the amount of heat directed at the popcorn so it pops more evenly and thoroughly. They are sold in packs of eight.
PowerCup Concentrators are made from a material that absorbs microwaves. This is the thin film on the surface of the concentrator. A similar microwave-absorbent material is used in microwave popcorn bags.
According to various sources, each concentrator lasts up to three to four uses. The Presto manual says users can make up to 12 batches of popcorn without oil and 24 with oil. However, if the top layer of the concentrator is torn, the device is unusable.