Specifications - model(Speed Up), materials(aluminum alloy), weight(Approx. 725g), diameter(Almost all manufacturers only produce native 27.2/30.9/31.6mm dropper posts. To be compatible with sizes like 28.6/30.0/30.4/30.8/31.8/33.9/34.9mm, we include a shim with the 27.2mm post for compatibility. For example, a 30.4mm post comes with a 27.2mm post and shim, saving you the hassle of purchasing shims separately) Suitable for touring bikes, city bikes, cargo bikes, tricycles, and bikes shared with others (friends, family). It allows riders to easily adjust seat height without removing the post, making it easier to mount, offering more leg extension, and providing comfort when stopping at traffic lights or stop signs Is this suitable for mountain and gravel bikes? - Depending on your terrain and skill level riding with one hand. For mountain trails, we recommend a remote dropper for safety. However, if you ride mostly on paved roads, the lever-actuated post should meet your needs Easy installation – No need for complex cable setups. You can replace the dropper post with just a hex wrench, making it especially convenient for bikes without internal cable routing or for riders who prefer a simple dropper post solution More affordable – Compared to remote dropper posts, this is a budget-friendly option that fully meets the needs of most urban riders Before Ordering - Please check the diameter on your bike to ensure you get the right post dropper post