I have alopecia universalis and I have used Elegant Lashes exclusively for years. I used 501 for years, and as I age I found that I was having a bit of trouble getting them on properly at times. I'm 81. I decided I needed a bit shorter lash. I went with these, used 1 pair, and realized they were not quite dense enough in texture for me. I then ordered 521, which are a tad longer than the these and are perfect in texture for me. Never have I ever been disappointed in the quality of lashes that I've ordered from Elegant Lashes.