A gas turbine engine installation comprising: a flexible printed circuit board harness arranged to transfer electrical signals around the engine installation, the flexible printed circuit board harness being a thin, elongate member having two parallel major surfaces offset by the thickness of the flexible printed circuit, characterized by: at least one clip holding the printed circuit board harness, each clip comprising a jaw extending from a base, the jaw comprising: a mouth having a width (w) for receiving the flexible printed circuit board harness; an upper set of teeth; and a lower set of teeth, wherein: each tooth (232, 242) is compliant and has a root (231, 241) and a tip (233, 243), and extends across at least a part of the width of the mouth; and the teeth of at least one of the upper set and the lower set extend from root to tip in a direction (u, I) that has a component pointing from the mouth to the base, with one set of teeth contacting and gripping one major surface of the flexible printed circuit and the other set of teeth contacting and gripping the other major surface of the flexible printed circuit. a flexible printed circuit board harness arranged to transfer electrical signals around the engine installation, the flexible printed circuit board harness being a thin, elongate member having two parallel major surfaces offset by the thickness of the flexible printed circuit, characterized by: at least one clip holding the printed circuit board harness, each clip comprising a jaw extending from a base, the jaw comprising: a mouth having a width (w) for receiving the flexible printed circuit board harness; an upper set of teeth; and a lower set of teeth, wherein: each tooth (232, 242) is compliant and has a root (231, 241) and a tip (233, 243), and extends across at least a part of the width of the mouth; and the teeth of at least one of the upper set and the lower set extend from root to tip in a direction (u, I) that has a component pointing from the mouth to the base, with one set of teeth contacting and gripping one major surface of the flexible printed circuit and the other set of teeth contacting and gripping the other major surface of the flexible printed circuit. a mouth having a width (w) for receiving the flexible printed circuit board harness; an upper set of teeth; and a lower set of teeth, wherein: each tooth (232, 242) is compliant and has a root (231, 241) and a tip (233, 243), and extends across at least a part of the width of the mouth; and the teeth of at least one of the upper set and the lower set extend from root to tip in a direction (u, I) that has a component pointing from the mouth to the base, with one set of teeth contacting and gripping one major surface of the flexible printed circuit and the other set of teeth contacting and gripping the other major surface of the flexible printed circuit. each tooth (232, 242) is compliant and has a root (231, 241) and a tip (233, 243), and extends across at least a part of the width of the mouth; and the teeth of at least one of the upper set and the lower set extend from root to tip in a direction (u, I) that has a component pointing from the mouth to the base, with one set of teeth contacting and gripping one major surface of the flexible printed circuit and the other set of teeth contacting and gripping the other major surface of the flexible printed circuit.