I've never paid much attention to slippers, always purchased the cheap-o type. SO HAPPY I did my research on these! I'm an 8.5 , purchased the 8.5 and they're perfect! Keeps my feet toasty warm, non slip to run around the house.  Excellent quality, worth the extra dollars. Just enough of a firm durable sole without feeling heavy . No rubber, they're super plush and cozy. Quality appears to have staying power, highly recommend!