Refilling laser printer toner cartridges

I have a Brother laser printer (HL-1850) that is beginning to flash the dreaded ‘toner is low’ message. Instead of buying a $50+ replacement cartridge I’d like to refill the existing cartridge. I’ve done this before with other printers and their carts by purchasing toner refill bottles off Ebay.

I have some unused toner refill bottles from a NEC printer and was wondering if “toner is toner”. Meaning – do I need to specifically look for toner refills for my make of printer or can I use the toner bottles I already have and refill the cart?
I don’t think there’s a difference in toner but I want to be sure before I go that route.

Thanks!
forthill