I have a L4960 regulator. In its datasheet on page 9 there is a typical application circuit. Under notes, it says C1, C6, C7: EKR(ROE). What does that mean?
ROE (Roederstein) was a German capacitor manufacturer, they made EKR-type capacitors. They are now owned by Vishay:
It doesn't look as though the EKR devices are still available. If you contact ST they should be able to suggest an alternative device. Switchers can be fussy about things like capacitor types, you probably need to use devices with similar characteristics.
Like Leon said, EKR devices were made by Roederstein. But I also found them at Frolyt, a manufacturer I never heard of before, frankly.
This datasheet suggests that it's a series of low-impedance elcos, which indeed is what you want for SMPSs. Other than that the document doesn't mention what EKR means, materials-wise or process-wise.