Hey just replaced my standard pump in my00 wrx for a walbro i brought from sean. I used the standard wiring as it pluged straight in both ends (easiest install ever) Just wondering wat the little black square thingo is on the wiring in the pic of the standard wiring it looks like somone else has wired it in.

Is it ok to use the standard wiring (with that black square thingo)? or should i have just soldered the new wiring and deleted the black square.