The ERT300 tennis computer is a unique microprocessor-controlled measuring device.
It accurately and quickly determines the stringing and playing characteristics of your tennis racket.

The ERT300 measures the dynamic tension of the string bed.
The measurement result is displayed in DT (Dynamic Tension).

The DT value is physically defined as the ball force in kp (kilopond) required to push the string bed by 1 cm for a short time (ball impact).

International Unit kp/cm, Newton/mm

The DT value defines the playing characteristics power and control.

A soft-strung racket with a low DT value generates more power through ball acceleration.

A hard-strung racket with a higher DT value offers more control and thus playing precision.

Every player has his optimal DT value.
He can determine this himself with the ERT300 during training and through his playing experience.

The DT value is mainly influenced by the following factors:
-Stringing weight ( reference tension set on the machine ).
-Accuracy and condition of the stringing machine
-Technique of the stringer
-Material and diameter of the string
-Head size and stringing pattern of the racket

All string materials lose tension immediately after stringing the racket, after playing and after aging.

Within the first 24 hours, there is often a tension loss of 2 to 4 DT, which is called stabilization loss.

Every player has his individual optimal DT value.
Playing strengths are roughly divided into 4 DT ranges, these can also overlap
-LO: DT 28 - 34 Defensive play, mostly from the baseline
-MID: DT 35 - 41 Dymamic offensive play
-HI: DT 42 - 46 Powerful, aggressive play
-HI+: DT 47 - 54 Very fast, aggressive play.

Restringing is necessary after a DT loss from 10% to a maximum of 20% of the initial value.
If the stringing is too soft, there is a risk of loss of control, unwanted vibrations and as a result elbow and back pain can occur.

The ERROR symbol appears in the event of an incorrect measurement.

Reasons / remedies are:
-DT value too low ( below DT 20 ) / restring racket
-Incorrect positioning / remove and reposition the device
-Frequency transmission faulty / change holding position from heart to handle

The ERT300 is designed and manufactured in Switzerland - SWISS MADE.
The final assembly and quality control is done by hand by our technicians.

Each ERT300 comes with a 3-year warranty against technical defects.
The warranty does not cover self-inflicted damage, such as damage caused by dropping

There are no cost for a pre-order. After your pre-order you will get an order confirmation.

When your ERT300 is ready you will recive a message including payment details. At this time you can also redeem your coupon codes, if any. After successful payment we will send your ert300 immediately.

The recommended retail price is 249€ ( excl. VAT )

No, shipping outside of Switzerland will incur customs and import fees and taxes.

Delivery is free of charge to the following countries:
Switzerland, European Union, USA, UK.
For other countries an additional shipping fee will be charged. More details check our shipping Policy

Our payment partner STRIPE makes the payment fast and secure.
We accept all major credit cards and PAYPAL as well as bank transfer