Reference height of person group : 5'7" ~6'1",21 Speed Shifting system Dual suspension mountain bike with dual Disc brake is easily portable to move around. Bike Installation instruction included in the package, please read it more carefully before installing the bike and tuning the brake and speed system. All tools are included in the package, no extra tools. This bicycle arrives with 85% assembled. You need to install the front wheel, pedals, handlebar, seat and air up the tires. We do not supply any bicycle assembly service for online pays or for free. Bicycle are the overweight products, if there are any scratches/damages caused during the shipping, please contact us directly for assistance. Bicycle Serials number at the bottom tube of frame, please find it and record it ,if the bicycle is stolen, this is sole signs that distinguishes the same serials products.