Comply Isolation T-500 Medium Black

Bought these to replace the tips on my KZ ZS-10 Pros.
Fits perfect between the earbuds and my ears.
Just be sure to clean the ears regularly as any foam tip will absorb wax and dirt.
I also take these for jogging - no problem of earbuds slipping out.
Approx 30 mins of everyday use and after 6 months I'm still on my 1st set.

I use these with a set of Harman/Kardon SOHO II NC Active Noise-Cancelling In-Ear Headphones.
These are far more comfortable than the supplied ear tips (particualry the plastic ones) keeping my ears cooler for longer. They also provide increased sound isolation and can therefore monitor at lower volume levels.
Generally they last several months depending on usage.
Only negative is that they do seem a little expensive but they are a quality product.
Overall highly recommended.

Bought these for my KZs. Due to the foam they seal super well and make the earbuds sound even better than they are with the default tips. Also great noise isolation due to them being foam tips.