Cooling rods were tubular objects specifically designed for Scorpius' coolant suit by the Diagnosan Tocot. Owing to his Sebacean/Scarran heritage, his body both generated intense heat and suffered from it. Combined with his suit, these rods were designed to absorb the extra heat, allowing Scorpius to function normally. They required regular replacement which was usually tasked to one of Scorpius' subordinates.
Initially they were much longer, and housed in a backpack in the original and much cruder design of the coolant suit. It appeared that Scorpius has gotten Peacekeeper engineers to perfect the technology, making the rods much smaller so they could be placed directly into his brain, increasing their effectiveness.
Cooling rods appeared neon blue when fresh and neon red when spent.