This is the Pole Repair Splint from MSR. Designed to repair a tent pole on the go, avoid having a broken pole all night long or even throughout your entire journey. Weighs almost nothing and offers a very easy-to-use backup option.
13mm: compatible with regular-sized poles (for 1 to 3 man tents)
16mm: compatible with large poles (for 2 to 4 man tents)