The ND-Series has long been one of Schrages best selling mechanical locks for good reason - its tough, durable, Grade 1 rated and fits a wide variety of applications. Now weve made our trusted ND-Series lock even better by making it easier to install. Weve added these enhancements because we know that a lock installed correctly the first time will last longer and perform better. The result: greater peace of mind that every door is safe and secured with a lock built to last.