I am interested in purchasing office chair gas lift cylinders (standard size: 50mm). Request information: 1. Can you offer free shipping to Vancouver, Canada? 2. If free shipping is not possible, what is the shipping cost for a small sample (1a??5 pieces)? 3. Do you offer discounts for bulk orders (e.g., 100a??500 pieces)? 4. What certifications do your products have (TUV, BIFMA, etc.)? I am considering building a long - term partnership with a reliable supplier for my chair repair business. Please send me your quotation including any available options for free or discounted shipping.