I just discovered these last year and used them myself. I have since had a hysterectomy - so have no need for them. But one thing I found these were very easy to insert. They slide in more easily than the cardboard ones.
I am not sure how biodegradable these are but would hope that Tampax did research on the environmental factors of their products.
All that plastic being thrown away these are no better than the cardboard applicator variants and they aren't that amazing either.