Hi
I joined a sextoy party once and I got the opportunity to test brand new kegel balls made of memory foam covered with two layers of silicone. Another woman on that party gave me this tip and told me its properties and I got the privilege of testing them first. My pussy swallowed them one by one and even though they were made of slow memory foam they were very hard but not as hard as kegel balls usually are.
I really had to fight to get them pressed together. When my pussy muscles finally pressed them, after a while I had the most lovely long-lasting orgasm I've ever had.