Review: Sennheiser's PXC 550 Wireless Headphones Should Put Bose on Notice - MacRumors
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User manual Sennheiser PXC 550 (English - 52 pages)
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Amazon.com: XANAD Case for Sennheiser Headphones,Fit for Sennheiser HD 450BT / HD 350BT / PXC 550 II / HD280PRO / Sony MDR7506 & MDRV6 Wireless Headset : Electronics