It's an ingenious solution, and coupled with the fact the tube is laser cut, cracks should be much less common. As you tighten the screws, the inner section compresses the large O-ring, forcing it out and providing a seal between the inner section and the tube. It obviously takes longer than just screwing down a threaded end cap, but it takes less than 5 minutes and as far as we could see, provided a tight seal too, with the end cap not coming off even with a fair amount of force, despite it being just the O-ring that holds it on.
The question will be whether the O-ring compresses over time and what impact that has on the seal, but seeing as we've yet to see O-ring fitted barbs suddenly start leaking after months of use, one hopes this won't be a future issue.
Click to enlarge
As well as size and colour variations, the CTR can be mounted to your case in a variety of ways. The standard ring bracket is the first method, and it simply fits around the tube, with a screw on one side to clamp it tight. The end of the bracket has a threaded hole, which you then use to secure to your case.
Alternatively there are side port end caps that fit in the same way, but provide separated inlet and outlet ports at a right angle - probably quite useful on the larger models.
The ends of these caps have two threaded holes for M4 screws, allowing you to mount the reservoir from the end instead of the tube using the bracket, which should allow some stealthy-looking systems, especially if you have the inlet and outlet facing away from view.
Build quality is generally excellent. The only fly in the ointment were a couple of flakes left on the threads of the delrin endcaps from milling - watch out for these; hopefully later samples will fix this issue though.
There wasn't a lot to test, other than to connect it to water-cooling loop and watch for any nasty cyclone effects. Thankfully there were none, most likely due to the width between the ports being quite large compared to other tube reservoirs we've seen - EK for example often ships an anti-cyclone plate. The O-ring seal proved solid and no amount of force on the end caps resulted in a leak - in fact they didn't even budge.
Primochill has done an excellent job with the CTR. Minor finishing quality issues and lack of blacking plugs aside, it's very well made and is one of the most flexible reservoirs we've seen in terms of mounting, size and ports. If you don't need to take it apart first, then everything is straightforward, although you'll need to spend a careful few minutes putting it back together along with thorough leak testing if you do.
The compression end caps are a great idea - not only have we had first hand experience of cracked threaded reservoirs but we've had a couple that have leaked too, so we're hopeful Primochill has largely solved these issues at a stroke. Thankfully, the CTR doesn't cost the earth either - in fact they cost roughly the same as their EK or Alphacool equivalents and are significantly cheaper than the likes of FrozenQ. We hope they're just as competitive in the UK too.