A 3pin and 5pin professional grade DMX terminator set.
From The Manufacturer:
The DMX T PACK is a 3pin and 5pin professional grade DMX terminator set, used for fixture installations with extended DMX cable distances and/or for electrically noisy environments. Connecting a DMX terminator to the output XLR socket of the last fixture in the chain, helps prevent corruption of the digital control signals by electrical noise or interference.