505 is my favorite. Someone gave me 24 cans of 101 basting spray for free. I have been using the 101, some of the cans don't spray very well, but it works. I will use it until it is all gone then switch back to 505 spray. I have never seen 101 in the store. Free is always good. I have found if I let it set for a day to dry before I quilt it, I don't get as much gumming up on my needle.