pocket magnifying glass

hey I need to get my hands on a good magnifying piece for its nearly harvest time. What are they called exactly, the one that kinda fold up and are like an eye piece. I know I need a 30x atleast but what size is best, what kind or style is best and what is the best place to get/order? thanks

I have the $5 30x loupe and I have a $5 45x scope type with LED. I find the 45x is better for getting the color of trichs and a 60x would not be too much. I use the 30x more for preflowers and pest identification. ebay has a gazillion and is where I got both.