E-bay UltraLight Titanium Seatpost

That style can be fine, but does require some special attention.

Saddle- Needs to a be quality unit with Titanium rails (typically) and have a strong ass interface between where the rails meet the saddle portion.

That design applies pressure to an unsupported section of the seat rails, so you have to balance the torque (tightening) values so that you secure the rails but don't go too far, as you will bend the rails downward. I have seen those posts work Ok for lighter riders and with saddles like the Selle Italia Flite with Ti rails back in the 90's

Don't skimp on the saddle!

Low "bolt" goes forward.

Forgot to add- You must apply high pressure grease (like CMD #3) or some Phil's Waterproof or antisieze to all metal/metal contact surfaces, or that post will squeek you into oblivion!

Just for laughs, I used to make my own MTB components 15 years ago, this was a seatpost design that also didn't have backing support over the lower carriage (7075-T6 aluminum and titanium) and this this was a squeeker! Man, it was bad, but since I made it, I refused to swap it out, drove me bats for months until I admitted that it was a poor design- looked cool, but that is where it ended.

I bought one of those off of eBay. Much to my regret after I received it. Just didn't trust the clamp/seat rail interface enough to actually use it so I cut off the end & attached a clamp assembly from a seatpost I bought on sale. Admittedly didn't do the best job of fitting but so far no issues with it.

It's the one on the far left in the pic below.

The others are my other attempts at 'custom' ti seatposts. I've used the 2nd from left for over 10 years without issue. It was made from a name brand ti seatpost that had a real hokey clamp. Got the seatpost for cheap so decided what the hey, what do I have to lose? It's my first. The two on the right were made for less than $50 but they're very flexy! Very thin wall ti tubing! And definitely not recommended for hard or heavier riders!

I'm not the OP but I purchased one of these posts earlier in the year and it bent on me in less than a month. I was weighing about 168lbs at the time. I ride a rigid SS so I am not sitting on the seat alot of the time. Don't know if I just got it wrong somewhere and hit a big enough bump or what. The tubing is very thin and they would not warranty the product when it bent. Personally I think you would be better off going with the KCNC Ti Pro lite post. It is made of Scandium and only weighs 150g (for a 27.2 x 350mm post. I believe that is lighter than the ti version you are looking at. KCNC also has a two year warranty on their parts from what I have read that is even extended to the second owner of the product (you know what I mean, if I were to buy it used, I could still warranty something if need be). So far I am happy with the post. I have ridden it 3 times now with no problems and currently weigh 187 lbs.

In either case, this post or the KCNC post, I would not recommend riding a carbon railed seat with them. Both of them have small clamping area that do not support the rails as good as others. The contact points where the mount meets the seat rails is very small and can generate a lot of pressure in a very small area. Some guys have gotten away with it but you must be very light on your bike if you will. I personally have a carbon seat on this post at the moment but that was only to see if I liked the seat. It will be coming off today after I weigh everything.