The Walchem WDEC410-12JNU controller is now obsolete and the closest equivalent is the WCN600 controller. The new WCN600 series has upgraded features; for reference, here is the description of the old model:
Dual input electrodeless (toroidal) conductivity controller, 120 VAC, prewired, two isolated analog (4-20 mA) outputs, in-line PEEK sensor w/stainless steel adapter (10.0 - 100 ms/cm, 20 ft cable), no second sensor, integrated datalogging and config file import/export via USB flash stick.