These genuine Metabo-HPT 3-1/2" 21-Degree Plastic Strip Collated Duplex Nail (Box of 2,000) (50312-16D) are manufactured at higher standards for material and workmanship to help eliminate downtime, so you can work more efficiently. Duplex nails are designed to be driven in and pulled out again. The Metabo-HPT NR3675DD Multivolt Cordless Duplex Nailer is the first on the market to be able to drive these mechanically instead of being driven by hand.