High Country Plastics Bull Mineral Feeder : 120lb Product Type_Branding They are made of rust

They are made of rust resistant non-corrosive copper alloy and have a 1/4" flat face

But considering the flow rate (low) it is probably closer to the 20 microns than the 7 microns

Use in broilers and replacement chickens as an aid in prevention of necrotic enteritis caused by Clostridium perfringens

Medium: Fits most standard medium dogs such as: Australian Cattle Dog

High Country Plastics Bull Mineral Feeder : 120lb Product Type_Branding They are made of rustHigh Country plastics Bull Mineral feeder is a one compartment with approximately a 120 lb capacity. It is a heavy duty impact resistant, durable poly construction with UV protection will withstand temperatures to 40 below zero with out breaking. A 3 4" thick, reinforced rubber mat is built to withstand the elements and keep minerals dry. 31" D x 19" H. BMF 120 All hardware is stainless steel to prevent rusting. Quick detach top allows the rubber mat