This product has been designed not only to secure the batteries without using the BATTERY TAPE under the chassis but also to position the weight where it’s needed.

The kit (FF75-XT09GH) contains aluminum and brass holder just to allow you to balance the car to your liking.
The mounting options are:

FULL ALUMINIUM
The lightest solution of the kit, approximately 9 grams;

FULL BRASS
The heaviest solution, about 20 grams;

MIX ALU-BRASS
The weight is about 15 grams;
This solution will allow you to move your weight forward to make the car easier and backward to gain more steering.

In any configuration you can also move the battery forward or backward by about 3mm