Present invention relates to retention system in sport helmets, having a strap with a concave under chin oval protective trauma device embodiment, attached and member to chinstrap of helmet. The lamp has a light-emitting vessel 16 of quartz and having end portions, an electrode member 10 contained in the vessel 16, and a conductive sealing member 7A. Based on knowledge of the characteristics of the remote modem design, various steps are taken which may improve performance of the communication connection in light of the particular modem design’s characteristics. Further, by introducing deposition gas onto the recording media surface by gas introduction means while irradiating the electron beam on the recording media, a component of the deposition gas is deposited in a detected defect position on the recording media surface to form a mark. A fine sluice box is located to receive under one-quarter material input from a side trommel and a coarse sluice box located to receive discharge from the side trommel and discharge from the fine sluice box.