This fuel pump is rebuilt and bench flowed to 1 liter in 15 seconds to the specification for 2 hours. It has a brand new armature and brushes. There is a 0 refundable core charge. This will be refunded when we receive your old part. We bill separately for this, so you will receive a separate invoice via Paypal after purchase. The warranty on the part is one year, unlimited miles. We offer full technical support for all of our remanufactured Mercedes parts.