Dear Dr. XXXXX, Thanks for your note. One seat includes the seat and the steel mounting bar - everything to put one complete unit on a bike. The seat is not included - that was a special promotion one of our customers did to promote the sales. Regarding a discount, the price that we quoted to you yesterday included $30.00 for the air freight from DHL. We normally do not get involved in this type of small business transaction but we are hoping to sell more of this product around the world. So, for this one time, we will reduce our price by $10. I think if we ship by boat, it will take a long time because of the small size and probably only save about $10. I think that the best way is to have Mr Johan Hsu to contact you. Johan, please send your phone number to Dr XXXXX. Regarding the weight limit, actually the unit could easily hold 200 lbs - but I hope no child ever weighs that much. You will be surprised to see how sturdy the unit it. I do not know the answer to the leg length question but the foot holder for the child can be adjusted up and down.