美国采购需求：自行车、自行车零件、三轮车、滑板车、儿童玩具、学步车

I'm looking to get some info on your MTB helmets. Could you please provide me with the pricing details for different models you offer? I'm especially interested in the bulk purchase options and any discounts that may apply. Also, it would be great to know about the available color choices and the materials used in the helmets. If you have any certifications or safety standards they meet, please include that info too. Looking forward to your response!