SL-2000 & SL-3000 Diferences?

ellenwoods5

Hey everybody i have a question on the diference between the polk tweeters that are coming from the factory namely the SL-2000 & SL-3000 i purchased two each about 4 years ago and i just recently was looking at all four of them. Now the cardboard containers are marked but the tweeters are not so when i was called away for just a minute then came back i forgot how i laid them out and they look exactly the same and there are no markings on the rear of them so how can i tell them apart can i use a test meter and if so what would the readings be between the two because i swear there is not a lick of diference between the two. Any help at all would be greatly appreciated