Just perfect. It fits into my ears without any problem and it seems durable.

I bought these direct to match my buds which are cambridge melomania 1

I bought the 10 memory medium foam ear tips to try. They turned out to be more comfortable and more secure, than the conventional tips. They alo insulate better against outside sound so improve the listening experience.

They marked up after a few wearings so I am not sure quite sure how durable they will be yet.

Its really worth persevering with different sizes and types of buds. I was using silicon to start with but was not quite happy with the overall sound and for me i found them difficult to position in my ears.
So i bought some medium foam for £10 and was astonished as to the difference they made. With a little tweaking here and there i have managed to find the ideal position in my (smallish ear canal) and the Melomania 1 sound even better. So i now have 4 spare pairs. Just to make others aware and Cambridge do make you aware of this. I stupidly bought another brand from Amazon and they did not fit. So make your own mind up. Another great purchase.