Couplers are traditionally manufactured from brass, leaded gun metal or stainless steel, making their high weight-to value ratio presents a theft risk. Proof Engineering therefore pioneered the ProAlloy zinc coupler, which offers reduced theft risk, lighter weight and lower cost. The ProAlloy is manufactured to specification from a zinc, copper and aluminium mix which holds no resale value, making it a “non-theft material”. The aluminium contaminates the mix and decreases the value from approximately R35/kg to R6/kg.


The patented non-theft material also makes the couplers 33% lighter compared their brass equivalents and presents a more affordable alternative. The zinc product has undergone corrosion tests conducted by Mintek against brass in mining water and results showed no corrosion affect. That the addition of a new additive has improved the metal strength of the coupler even further. The company buys the metal back from customers at R15/kg and recycles the metal.