Hi Hooterville75,

The colour of the outer aluminium casing does not specify anything as it is manufacturer and range dependant so will not affect the actual resistor.

As it is aluminium cased i assume it is a chassis mount wirewound type and as such lgb82 is correct when he says it will create a ton of heat when running at load so you will need to securely mount this to a solid metal plate ( i have always used a thick slab of ally) or heat sink to help dissapte some of this heat.

My company use this load system to test power amplifiers and they generate an extreme amount of heat.

I would test out how much heat is generated when running at load for a prolonged spraying session and this will give you some idea of how much you need to get rid of. (there is a formula for working this out but it's far too complicated.)

Hope this helps

Jay