Estring, vaginal ring to provide estrogen replacement therapy

Has anyone used Estring for estrogen replacement therapy. Would you please share your experience, pros and cons.
At my age oral estrogen is not prescribed. I have tried inserted estrogen creams and the result is itching and burning.
I have several forms of eczema and react to dozens of contacts, however I did not see any element in this product I should reject.
I'd appreciate your input.