A word of advice, if you buy a German helmet from an on-line auction, be very careful and ask the right questions. If the seller sends you fuzzy pictures or seems apprehensive to answer questions, do not bid. A very high percentage of German helmets listed at on-line auctions are fakes or have at least been tampered with. Most likely the number of non-original helmets approaches 95% or more. You can get lucky and find good German helmets at an on-line auction. Collectors usually know the good ones when they come up and they usually they command a high price. On the flip side, if a deal seems to good to be true, then most likely you are dealing with a reproduction. Stay away from helmets outside the US. Virtually all have been tampered with in some way. Ebay is a very dangerous place to buy German helmets. It has become a dumping ground for the post war fabricated pieces. There are also several Ebay sellers in the US acting as fronts for various East European fakers. They all have the same story, such as direct from a Vet estate, or a small museum. The best way to have a high quality collection is to buy your WW II German Helmets from reputable dealers, that offer an inspection period and stand behind the product with a Lifetime Guarantee.
Medals involve not only the metal itself but also the ribbon, and these materials are susceptible to damage from moisture, dust, sunlight, and changes in temperature. Museums keep medals in locations with regulated temperature, humidity, and light levels to minimize discoloration and deterioration. At home, collectors should keep medals clean and dry, and should store them in a location that is not prone to extreme temperatures. Damp conditions corrode the metals and rot the ribbons, while high temperatures make ribbons go brittle. Acid-free cardboard boxes are a good storage solution, but wooden boxes coated with polyurethane resin are also acceptable. Collectors should avoid polishing medals, as the polish causes abrasion, and they should always wear gloves when handling the medals.