In the Press...
A grippy silicone strip because no one wants their bag slipping off their arm (the worst). Add this to the strap and it'll stay in place all day.
Promising review: "I recently bought a high quality leather shoulder strap handbag and was having problems with it sliding off my shoulder, since the leather strap was fairly smooth. So I went online and searched to see if there were any products out there that would solve this issue...and I found the Purse Gummy! It works beautifully! No more struggling with a slipping strap. It is hardly noticeable on the strap since it is on the underside, but I wouldn't mind it if was seen because it works so well." —D. Dillon