A knuckle is formed by a knuckle body and a lower arm support bracket fastened to front and rear fastening portions provided in a lower portion of the knuckle body with front and rear bolts. 001 wt % metal, based on binder solids, of at least one metal salt of an organic acid wherein the metal is selected from the group consisting of V, Ce, or Fe; at least 0. The defibrillation energy delivery circuit requires fewer electronic components, reducing the size andor cost of the implantable cardiac rhythm management device. The lock arm is connected to the second connector by a resilient U-shaped strap.