Today something completely different here on mijnracket.nl. In the context of comfortable and injury-free sports, Mike was allowed to test a new sports sole for a few weeks. The Comfort Energy sports soles from manufacturer Comfortable excel in shock absorption. Read more! 
The Comfort Energy sports soles (energysoles.nl) are made of the material 'Sands'. Sand is a material that forms to the foot and therefore should provide extra support in the arch of the foot in a natural way, comparable to walking barefoot on sand. The material has very good cushioning properties and, as the name of the soles suggests, also returns energy when pushing off. This should be noticeable especially on hard surfaces. I tested the soles on gravel for 8 hours. Our Dutch FED Cup team member Cindy Burger has apparently been using the Comfort Energy sports soles for years.
Specifications:
Brand: Comfortable
Sole type: Comfort Energy Soles (energysoles.nl)
Thickness: 4.5 mm
Size: 43
Weight: 40 grams
Tested by:
Name: Mike
Playing strength: 4/4
Shoe: Mizuno Wave Exceed Tour Clay , size. 43
Test duration: 8 hours
Current own sports sole: Footbalance 'Game'
Fit:
The fit of the Comfort Energy Soles is perfect. Size 43 is also really size 43. The soles fit my tennis shoes without any problems, of course after first removing my current Footbalance soles. Fresh in the shoes, the soles initially felt a bit thick. This took some getting used to, because soon after the sole began to form to the foot. 
Judgement:
Comfort and support New in the shoes, the Comfort Energy Soles feel very soft and comfortable. This remained the case during this test period. The 'Sands' material forms to the foot, but does not permanently maintain the foot shape. The material always returns to its original shape. On the one hand, this is nice, because it provides long-lasting, good cushioning and comfort. On the other hand, the support is less than I am used to.
Prior to this test I played the entire outdoor season (gravel) on my custom-made Footbalance 'Game' soles, see this review . The Footbalance soles are made of a thermoplastic material in the forefoot and midfoot that will form to the foot after it has been heated. This shape and support in the arch of the foot is permanent. So this is what I have become accustomed to. The Comfort Energy Soles provide more cushioning than my Footbalance sole, but the Footbalance sole clearly gives me more support in my arch of the foot, something I experience as very pleasant.
Agility and foot fatigue
The Comfort Energy sports soles are nice and light at approx. 40 grams per sole. As mentioned above, I tested these soles on gravel. My Footbalance soles give me a nice direct response when moving sideways and pushing off. With the Comfort Energy Soles, I sank a bit more into the sole when pushing off. For me, this was at the expense of the quick turning and turning, which is very important in my game. So I tested the soles on gravel. On a harder, less cushioning surface such as hardcourt or carpet, the sole might work a bit better. Of course, gravel already cushions somewhat. I will also test the soles in the hall on carpet this winter and will report back with my findings.
After a long session, it is noticeable that feet feel less tired. The comfort level of the soles is therefore very high. 
Conclusion
The protection of the sole of the foot and the long-lasting cushioning of the Comfort Energy sports soles are great, the support and the 'energy loss when pushing off' I found a bit less. I think this sole works particularly well for sports where you mainly move forward, such as running. Nevertheless, for €19.99 you get a lot of comfort for the feet. So if that is what you are mainly looking for, I can definitely recommend the Comfort Energy Soles. As mentioned, I will also use the soles on a harder surface, after which I will add my findings to this post.