Over the years I have found that no other IEM tip, in any other material or configuration can even come CLOSE to the seal and sound quality of the basic Etymotic foam
Etymotic ER38-14A Small Beige Foam Eartips - 4 pairs
ER Earphone Series Tip Pack - Etymotic
Amazon.com: Etymotic Research ER20XS High-Fidelity Earplugs (Concerts, Musicians, Airplanes, Motorcycles, Sensitivity and Universal Hearing Protection) - Universal Fit, Standard/Large/Foam Tips, Clear Stem : Health & Household
Etymotic Ear Tip Options | Headphone Reviews and Discussion - Head-Fi.org
ER Earphone Series Tip Pack - Etymotic
Etymotic Research Ear Tips Replacement Memory Foam Ear Tips Etymotic Research | eBay
Etymotic Ear Tip Options | Headphone Reviews and Discussion - Head-Fi.org
ER Earphone Series Tip Pack - Etymotic
ER Earphone Series Tip Pack - Etymotic
Etymotic ER38-14A Foam Replacement Tips - Small - for ER-4, HF2, HF3, HF5, MC2, MC3, MC5 & More! (Pack of 4 Pairs) - Etymotic Earphone Accessories
Etymotic Ear Tip Options | Headphone Reviews and Discussion - Head-Fi.org