Thats it. They come in a larger size, mine are both mouse size. I believe Harbor freight sells a Chinese version too.
I''ve had these for years and have emptied out a PILE! of mice at times when they were placed in an area that you couldn't smell them in decay process.Common to have to take a stick & sort of dig the bodies out! This is not to say we have lots of mice but rather to say they work well over a period of time. If it was in your home you'd smell them quickly.We live in the woods & they come to food or shelter. I just hose them out and reload PB on the touch pad. If we get a mouse in the house that's one of those hard to catch fellers with a small spring trap, I'll enlist one of the boxes on a piece of newspaper and usually takes 1-2 days.
I researched the electronic gizmos & don't feel they are really worth a try after my web reading.I did get on a "lifetime" junkmail list of the mfg's ! We have a log house & the bats cause too much noise for some upstairs sleepers so I gave them a hard look.