Other merchandise includes keychains, lanyards, mousepads and bookmarks. Most drives can be attached to keychains or lanyards. Backstage passes can come in the form of lanyards, stickers or wristbands. They also wear white pistol belts, lanyards, helmets, boot laces or leggings. Construction site lifeline systems include dedicated attachment brackets, safety lanyards and harnesses. Available accessories for all E series included lanyards, armbands, A/C adapters, metallic and silicone cases. Chinese swords, both "jian" and "dao", often have lanyards or tassels attached. Many military units wear dress lanyards. Knots can be applied in combination to produce complex objects such as lanyards and netting. Some accoutrements such as lanyards, have both a traditional/ceremonial and a practical purpose. Many ID card lanyards have a built-in feature known as a "breakaway" closure. Breakaway lanyards release when pulled or when pressure is applied. Some protocols require all equipment to be attached to the structure by individual lanyards. Personnel of both 40 Commando RM and Gerak Khas wear the traditional blue lanyards. Lanyards were used by cavalry and naval officers at sea.