If you're looking to customize the weight of your racquet then you're looking for Gamma's Lead Tape. It allows you to add weight anywhere to the racquet.
The most common areas on the the head are 2, 6, 9 and 12 o'clock. It can also be added under the grip.
Gamma Lead Tape (1/2" x 36")
- 0.5 grams per inch
- 0.50" x 36" (12.7 mm x 91.4 cm)