https://www.techpowerup.com/292997/ek-water-blocks-announces-flexible-leak-tester
 
EK, the premium liquid cooling gear manufacturer, is releasing a new leak tester purposed for PC liquid cooling. EK-Loop Leak Tester Flex is a fast and safe way to test for possible leaks in your custom water cooling loop. While traditional leak testing works, it is slow and requires actual liquid leaks in order to diagnose the issue. Using air as a test for leaks, does the job way faster, less messy, and ultimately just better.

Traditional leak testing requires the user to fill up the entire loop with coolant, wrap joints with paper towels, and wait for hours constantly checking if any of the paper towels are wet. With air testing with the help of a leak tester, the user doesn't have to fill the loop, allowing much easier disassembly in case of a component leaking, way fewer risks for the PC hardware, and to top it off, less hassle and time spent for the user.
 
EK-Loop Leak Tester Flex has a flexible tube on one end, allowing you to easily reach any port in your loop and avoid stressing it when pumping. It is fitted with a revolvable male G1/4" connection port so it can be directly screwed into any standard G1/4" port in your liquid cooling loop. The other end is hooked up with a non-return valve which will make sure that no air is escaping through the tester unit itself. A small pump for pressurizing the loop is also included.

The top-mounted pressure gauge is custom made for liquid cooling loop testing purposes which clearly marks the safe pressure for testing. In order to prevent damage to your liquid cooling loop, keep the pressure only in the predefined zone marked on the gauge. Please read the user manual before using the EK-Loop Leak Tester Flex.

The EK-Loop Leak Tester Flex is available for purchase through the EK Webshop and Partner Reseller Network. In the table below, you can see the manufacturer suggested retail price (MSRP) with VAT included.

MSRP: 29.90€. For more information, visit this page.
 
The price is worth the investment in my opinion if you have liquid cooling loops. 
 

GTXJackBauer
What happens if you have a slow leaker?  Will you feel the air?  Do you have to put soap and water on every fitting, port, block, etc. to figure out where the leaks are coming from?  I think I'll stick with traditional since it will show me exactly where the issue will be.  Plus, the system will always be off so don't understand why they're trying to recreate the wheel here.

I have the original EK leak tester and use it as an initial test.  If it holds pressure for @15 minutes, then it should be good.  If not I check fittings and blocks and will generally find the leak.
 
However, I'm old school, after this test, I leak test with distilled water for 24 hours.

The new design with longer hose looks like a good improvement. 
 
I see the "green range" on the gauge is lower than the rev 1.0 tester
 
Retail is listed as Less expensive than the first design  $30 vs $41
 
I'll also add to what other have mentioned -->advantages of air testing


1) you can also test individual components before you assemble the loop.
 
2) Leaks can be things other than loose fittings & tubes ..... damaged O-ring or even a speck of something between the O-ring & the sealing surface ... so, just tightening fittings is not always the solution.
 
Directions are a Must Read .... not every part of the loop is rated for the max "green zone" ....details are in the directions ... I think EK should have addresses this on this rev 2.0 leak tester

False sense of security… how? If it air is getting through, you are going to hear the air leaking…

False sense of security… that concept blows my mind. I’m really getting stuck on that archaic way of thinking.. I used the same 480mm rads for years and the air leak tester was the reason I found a cracked radiator and didn’t need to take all of the water out of my system or dry anything, because the only thing that leaked was Air, which is dry… and doesn’t damage components.

I have the original EK tester. The first one I received leaked right where the gauge meets the brass block. The replacement didn't. Makes me wonder why they felt the need to make a new version? Besides listening for air leaks also watch the gauge for leakage. Also, this new version looks very similar to the Barrow/Biski model, which works great. though the EK looks like it includes a longer hose.  

LOL I'm crazy. I old school leak tested my first time. Now I just put everything back together and turn her on with no testing  (I have towels in the case for the first day just in case)
 
I would actually use this product if it was given to me, almost bought the first a few times. But my way is working for now so can't get myself to actually purchase it 

the_Scarlet_one
The reason they made a new one was to reduce the green zone in the pressure gauge. The pressure tester was released before distro plates were common.

Previously the green zone started at .5 bar, and that was too high for distro plates which should see no more than .3 bar. Now the green zone starts much lower to accommodate distro plates.

That's some useful information, thank you.