Talent's 3-pin DMX terminator is used to terminate a chain of DMX fixtures in order to reduce the chance of errors and the resultant unreliable or erratic operation among your DMX fixtures and controllers. Simply place the DMX terminator in the DMX OUT jack of the last fixture in your series to close the daisy-chain. Your DMX fixtures "might" work without a terminator, but why take a chance they will when you can be certain of it?