Universal Trial Frames UB 3/UB 3+, UB 4 and UB 6 are all suitable for any trial lens conforming to DIN EN ISO 9801 and having a rim diameter of 38 mm, such as a OCULUS “tl” trial lens.
However, our Universal Trial Frame UB 5 for small heads requires trial lenses of the “tls” line with a diameter of 28 mm. These also conform to DIN EN ISO 9801 and are available nowhere in the world but from OCULUS.