Used these once on my niece's hair for only 10 minutes. They are in pristine condition.
From the manufacturer's website:
Spoolies, the curlers millions loved in the 50s and 60s are easy to use, fun to wear, and create a variety of hairstyles, such as ringlets, curls and beachy waves. Simply wrap the hair around the stem and snap the top over! The longer you leave the curlers in the hair, the tighter the curl. These Jumbo-size Spoolies create the size of curl similar to a 1 to 1 1/2 inch curling iron - but no heat or chemicals required. Spoolies are heat resistant and can be used with a hair dryer as indirect heat to activate the curls more quickly!
Features include:
Pure Hypoallergenic Silicone
Soft and Flexible
Heat Resistant
Non Slip - will not slide out of hair
No Pins or Clips Needed
Odorless & Non-Toxic (no PVC or Latex)
Washable