The Necromancer's Bells are a set of seven bells which play a pivotal role in the Old Kingdom series of books by Garth Nix. They are used both by the Abhorsen and the Necromancers, and can either bind or raise the dead. The Book of the Dead stresses with most of the bells there are unintended and dangerous consequences if the wielder is improperly trained. They are named after the Seven Bright Shiners who formed the Charter.
The Abhorsen's set of bells are silver with mahogany handles. They are also infused with Charter Magic to offset the necromantic Free Magic used to create them. The necromancers' sets are often made of bronze or silver with handles of ebony or bone, and empowered solely by Free Magic.
The pipes are a syrinx of functions identical to those of the bells, designed for the Abhorsen-in-Waiting to use until proficient. Lirael gains them in the eponymous book, but gives them to Sameth after realizing that she could handle the bells and he could not. At the binding of Orannis, Sameth uses the pipes to create Lirael's sword.
http://www.oldkingdom.com.au/bells.html