this is the kind i got from meijers. it was like 9 dollars. it reads temp. and humidity. but i did the thing where you put it in the bag with salt and it just went to like 99% then back down to 40%. i know vicki says that you should turn the little thing until it is reading accurate. first of all there is no little thing to turn. second of all i dont know if i am calibrating it right. can someone please help me i really need this now!