RETENSER
THE STORY

A GUITAR PLAYER HAD THE ANSWER.
A TENNIS COACH ASKED THE QUESTION.

Sander van Heijst has been coaching tennis for over 25 years. For most of that time, the advice he gave struggling players was always the same: get your strings replaced. The most common reply was always the same, too: "I don't have time."

So the players kept playing. With strings losing tension every week. Getting slower, softer, harder to control. And Sander kept watching it happen — season after season.

Story image
Why can you instantly adjust a guitar string, but not on a tennis racket?

ONE QUESTION

CHANGED EVERYTHING.

One evening, Sander picked up a guitar. Plucked a string. It had gone out of tune — so he tuned it. In fifteen seconds. And it struck him: why can you instantly adjust the tension on a guitar string, but not on a tennis racket? Why do tennis players spend €30–50 every few months replacing something that could simply be restored?

No one had answered that question properly.
So Sander decided to.

BUILDING THE RETENSER

From a rough idea to an award-winning innovation.

THE FIRST PROTOTYPE

The first prototype was built in Sander's workshop — rough, functional, immediately effective. He tried it on his own racket. The results were clear enough to keep going.

THE FIRST PROTOTYPE

Over the years that followed, Sander worked with a specialist design agency to evolve the Retenser from a rough concept into a precision-engineered product. The Conic Cylinder Technology (CCT) mechanism — patented across the EU and the US — emerged from that process. Not an obvious solution. Not a simple one. But the right one.

In 2021, the tennis world took notice. The Retenser received the Red Dot Design Award in the "Most Innovative Sport Product" category — one of the world's most prestigious product design honours. Shortly after, the International Tennis Federation granted official approval, clearing the Retenser for use in all professional and amateur competitions worldwide.

Today the Retenser is in the bags of players from the Netherlands to the USA, from Mexico to Belgium — club members and ATP professionals alike. Sander still coaches. And nobody he works with plays with dead strings anymore.

Award
badge

ITF
APPROVED

BRAND MISSION

Every tennis player — at every level — deserves to play with strings that perform as well as they possibly can. That is what we built the Retenser for. Nothing more, nothing less.

— Sander van Heijst, Founder, Retenser / Elevating Sports BV

Red Dot Award 2021
Red Dot Award 2021

Most Innovative Sport Product — internationally recognised design excellence.

reddot winner 2021
7
ITF Approved

Officially cleared by the International Tennis Federation for all competitions.

EU & US Patents
EU & US Patents

Conic Cylinder Technology protected by patents in the EU, US, and beyond.

EP 3974037 A1
US 2022/0088444 A1

Ready to experience what Sander built?

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