The Walchem WEC410-1NNU controller is now obsolete and the closest equivalent is the WCN600PSNNN-NN controller. The new WCN600 series has upgraded features; for reference, here is the description of the old model:
Electrodeless (toroidal) conductivity controller, 120 VAC, prewired, no 4-20 mA output, no sensor, integrated datalogging and config file import/export via USB flash stick.