New Strings from the Jungle: GORILL-1

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New Strings from the Jungle: GORILL-1

The market for tennis strings has been constantly evolving and expanding over the past 15 years. Every year, there are dozens of new string variants that make it to the market, both from established and new companies alike.

We learned of the birth of one such company, String-Kong, a few months ago. A brand that promises to add a dash of fun and excitement to the world of tennis strings and related equipment, we became aware of its existence not from an advertisement or promotion, but by noticing that several ITF players are sponsored by String-Kong. We also increasingly saw String-Kong merchandise pop up in stores, and various players wearing the company’s T-shirts. We decided to contact Ivan Buffoni, the owner and founder of the brand, in order to get our hands on some of these new products to see how they stack up to the competition.

First things first. The String-Kong range consists of 3 monofilament and 2 multifilament variants. Our first choice for testing fell on the Yeti, the brand’s flagship monofilament string, which is aimed at the intermediate/advanced level player. But after speaking to Ivan, we decided to test the Gorill-1 first instead. In particular, we looked at the 1.20 and 1.28 gauges, which had only recently been released, as well as the 1.24 gauge, which has been around for a while.


The string

The Gorill-1 is the latest generation polyester monofilament, available in black, with a special external coating to emphasize the so-called “snap-back effect.”

Evaluation method

We tested the strings both on the court and in our “laboratory,” but our emphasis on the latter was limited. Though we do find it interesting to analyze chemical compositions and to observe string behavior when placed under machine pressure, the most fundamental issue is how the strings feel in play. So that was our main focus when testing the strings.

Quality control 1 (weight)

We weighed 5 individual 200m string lengths of the 1.24 gauge, as well as 12 separate packs of 12.2m (we could not run the same tests with the 1.20 and 1.28 because of limited test samples). The data were gathered was quite interesting, with the maximum difference between the heavier samples coming in at 1.5g, while the average deviation was just under 1g. With the 12.2m packs, the maximum difference was 0.3g and the average just 0.1g. This is a very impressive consistency.

Quality control 2 (diameter)

In these tests, all three gauges performed similarly. We took 4 sets of each kind and made 10 measurements. The result was a maximum difference of +/- 0.02mm, with an average discrepancy of zero, which means that the diameter was exactly as specified by the manufacturer.

Quality control 3 (length)

Here, too, the 9 sets we measured were very consistent, with a mere 2 cm maximum difference.


The Gorill-1 is a nice string to set up, with good smoothness and no significant shape memory.


On the court

The following evaluations are based on the tests performed by our 4 testers: Marco (22 years old, 2.4); Peter (28 years old, 3.2); Sabrina (19 years old, 3.4); Gino (38 years old, 4.3). Each player tried all 3 gauges.

The feature that immediately impressed all our testers was the great driving force of the Gorill-1, with a very pronounced “trampoline effect.” It is quite easy to feel the strings bend more on impact and snap back very quickly, a phenomenon sometimes referred to as “pocketing.”

The effect of pocketing on each shot is that it allows for greater ease of execution for slices, drop shots, and slice serves. Indeed, it gives these shots significant extra bite. At the same time, topspin shots and even flats shots are given extra weight and impact. Another sensation picked up by all our testers was a very good feel on each shot, with the ball feeling very lively with every stroke.

The impact phase does not feel dry or wooden, but is instead quite responsive and dynamic. We would not call The Gorill-1 an overly soft string, but it’s certainly not a stiff one. It’s very comfortable to use and quite forgiving, with a big sweet spot that will still support off-center shots.

Control and spin generation are good for all three of the tested gauges, but a special mention goes to the 1.28, which offers better spin and control without sacrificing any power.

Tightness and durability seemed to us to be two particular areas of excellence for the Gorill-1. We expected a drop-off with the 1.28 compared to the finer gauges but, to our surprise, the tightness was very good.


The Gorill-1 is definitely a high-end string, with a quality control in the production process that ensures a consistent experience from racket stringing all the way to the court. Advanced players will get the most out of these strings, but intermediate level players will definitely also benefit from them.

When asked, three out of our four testers preferred the 1.20 gauge. According to their feedback, this is because that variant had the best power and sensitivity. Of course, you should select the gauge which best suits your requirements and style of play. But overall, this is an excellent string at a good price point that is highly recommended.

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