Sure Seal Ring, Medium, Square [Pack of 10]

Having trouble putting them on , no instructions on the package . Not quite sure how to use them wasted three already , any help would be appreciated

Ok for swimming? My husband wears a base that is 4" 3 1/2" square. Is this big enough or do they make bigger seals?

Do these go on top of your flang or under it onto the skin?

Can this product be used with soft convex wafer?