uxcell 6063 Aluminum Round Tube, 300mm Length 12mm OD 3mm Inner Dia Seamless Aluminum Straight Tubing 2 Pcs

I was surprised to find this item on Amazon, but the 12mm OD aluminum rod with 5mm ID bore was perfect for tapping with an M6 thread at each end and screwing in an M6 bolt at one end, then cutting off the head to leave a threaded post. Why? To make a perfect counterweight arm extension to the 12mm diameter arm of my Sky Watcher Star Adventurer Pro star tracker. In the long run, I found it was better to also add a bit more weight, but that too was easily fashioned from a galvanized steel pipe cap into which I screwed a bushing that held a fender washer tightly in place to trap about 300 BBs in the cap cavity. With a hole drilled into the cap end for a long M6 bolt to be run through it, the result was a functional 1-lb. fixed counterweight that I then screwed into a 150mm length extension. The counterweight arm already had an M6 screw in the end, to serve as a safety for keeping the counterweight from slipping off, so by simply removing that screw, the counterweight extension could be screwed on and the problem was solved.

12.15mm OD & 8.94mm ID. The tubes were not true either. I was able to make them work with some modification.

Needed this specific OD and ID spec for a bike rear axle reducer project from 12mm to 10mm for a 10x135mm thru-axle QR setup and measurements were spot on. Fits perfectly after cutting it to specific length.

Reported as 13mm inner diameter, but actually 12. Not usable for my application. Not worth the cost of shipping to send back.

Purchased "300mm Length 12.7mm OD 8.8mm Inner Dia", length is right, OD as well, ID bit off, for me does not matter but I measured 8.6mm instead 8.8mm

Perfect! Just what I needed.

Lo pedí 12mm x 5mm y no llegó con esas medidas

I've never heard of 6063 aluminum. I'm familiar with 6061 tubing and 7005 since these are standard grades used on bicycles. The 6063 seem softer but serves its purpose. I would recommend this tubing since it is the accurate in its sizing