I bought these jumpers for little experiments with Arduino. When the envelope arrived this already gave off a strong unpleasant Chemigeruch. I then the jumpers tried to lift a week on the balcony at this truly penetrating odor get away. I am what something normally concerns not squeamish, but the intensity of this product is an unbearable stench spread clearly unbearable for me. I can not say exactly what it is, whether it is a plasticizer or other components. It stinks just unbearable and you get a headache, so that a user within your own four walls is not possible. Yet if the product is not so cheap that the shipping I would exceed the actual value, it also return, so I can only the allocation to the waste recycling.