ok, Mcmaster Carr lists 4 typs of VITON seals.
from the website:
Standard: Has excellent ozone, weather, synthetic lubricant, animal/vegetable oil, aniline, chemical, and hydraulic fluid resistance.
FEP-Encapsulated: Perfect for sealing corrosive fluids, and FEP encapsulation makes these O-rings virtually impervious to most solvents and chemicals. Excellent resistance to friction and compression makes them ideal for static sealing applications. The FEP encapsulation meets ASTM D2116 and LP389A and is FDA compliant. Offers greater chemical resistance than silicone. Durometer hardness is A85 and temperature range is -15° to 400°F. O-rings are clear with a black inner ring.
Double-Seal: These Viton O-rings resist oil and some chemicals and can be used in place of standard O-rings. They have four sealing surfaces for twice the sealing protection. Also known as Quattro Seals, double-seal O-rings are symmetrically designed for sealing on the ID, OD, top, and bottom. This design reduces the amount of force needed to create a positive seal, increasing seal life and reducing maintenance.
Military Specification: These Viton O-rings have excellent chemical and oil resistance and meet MIL-R-83248C, Type 1, Class 1.
the standard comes in the correct sice and are 2 for $2.95, is that the ones I need?