Teflon tubes (FEP) are chemically inert and are suitable for low pressure.
TEFZEL support tubes working pressures higher than Teflon, but its use is limited to aqueous solutions.
In both cases the material is extruded with a very high precision bearing tolerances of .001 "for the OD for 1 / 16 and .003" for tubing 1 / 8 ".