We don't have all that much data on refractometers. Many of them are made to order and relabeled, so even knowing which company actually manufactured it is tough. You could try either model.
There are problems with calibrating with RO/DI:
http://reefkeeping.com/issues/2006-12/rhf/index.php#11
I used the PinPoint conductivity solution when I was using a refractometer. Something around 35 PSU, 1.026 SG @ 25C, or 53 mS should be fine if the solution intended for a refractometer.