Wilson's Slam JR 21 features a fun, youthful design with bright, vibrant colors. It's a lightweight and easy-to-handle tennis racket with performance-ready playability that's perfect for beginners. The AirLite Alloy aluminum frame provides lightweight durability with impressive strength. Frame technologies optimized for beginners make this racket stable, powerful and easy to maneuver, so new junior players can experience success every time they step onto the court. This pre-strung 21-inch racket comes tuned and ready to play. Recommended for players aged 5-6.
Reviews
Men's Apparel
| Size | Chest | Waist | Inseam |
| S | 36-37 | 30-32 | 32 |
| M | 38-39 | 33-34 | 32.5 |
| L | 40-42 | 35-36 | 33 |
| XL | 43-45 | 37-39 | 33.5 |
| 2XL | 46-48 | 40-42 | 34 |
| Size | Chest | Waist | Inseam |
| S | 91-94 | 77-81 | 81 |
| M | 97-99 | 84-87 | 82 |
| L | 102-107 | 90-92 | 84 |
| XL | 109-114 | 94-99 | 84 |
| 2XL | 117-122 | 102-107 | 86 |
How to measure
Chest
Measure around the fullest part of the chest.
Waist
Measure around the natural waistline.
Seat
Measure around the fullest part of the seat.
Women's Apparel
| Size | Bust | Waist | Hip | Inseam |
| XS | 31-32 | 25-26 | 34-35 | 79 |
| S | 33-34 | 27-28 | 36-37 | 80 |
| M | 35-36 | 29-30 | 38-40 | 81 |
| L | 37-38 | 31-32 | 41-43 | 82 |
| XL | 39-40 | 33-35 | 44-46 | 84 |
| Size | Bust | Waist | Hip | Inseam |
| XS | 78-81 | 64-66 | 86-90 | 79 |
| S | 84-87 | 69-71 | 91-94 | 80 |
| M | 89-92 | 74-77 | 96-102 | 81 |
| L | 94-97 | 79-81 | 104-110 | 82 |
| XL | 99-102 | 84-90 | 112-117 | 84 |
How to measure
Bust
Measure around the fullest part of the bust.
Waist
Measure around the natural waistline.
Hip
Measure around the fullest part of the hip.
Boy's Apparel
| Size | Bust | Waist | Seat | Height |
| XS (6) | 23-24 | 22-23 | 24-25 | 46-48 |
| S (7-8) | 26-27 | 23.5-24.5 | 27.5-28.5 | 49-54 |
| M (10-12) | 27-28 | 25.5-26.5 | 29-30.5 | 55-59 |
| L (14-16) | 30.5-32 | 28-29 | 32-34 | 60-64 |
| XL (18-20) | 33-35 | 29.5-30.5 | 35-36.5 | 66-69 |
| Size | Bust | Waist | Seat | Height |
| XS (6) | 58-61 | 56-59 | 61-64 | 118-124 |
| S (7-8) | 66-69 | 60-62 | 70-72 | 125-138 |
| M (10-12) | 69-71 | 65-67 | 74-77 | 142-150 |
| L (14-16) | 77-81 | 71-73 | 81-86 | 156-162 |
| XL (18-20) | 84-89 | 75-77 | 89-92 | 169-175 |
How to measure
Chest
Measure around the fullest part of the chest.
Waist
Measure around the natural waistline.
Seat
Measure around the fullest part of the seat.
Girl's Apparel
| Size | Chest | Waist | Hip | Height |
XS (6) | 23–24 | 22–23 | 24–25 | 46–48 |
S (7-8) | 26–27 | 23.5–24.5 | 27.5–28.5 | 49–52 |
M (10-12) | 28–30 | 25–26 | 30–32 | 53–57 |
L (14-16) | 32–34 | 28–30 | 34–36 | 58–62 |
| Size | Chest | Waist | Hip | Height |
XS (6) | 58-61 | 56–58 | 61-64 | 118–124 |
S (7-8) | 66-69 | 60-62 | 70-72 | 125–133 |
M (10-12) | 71–76 | 64–66 | 76–81 | 135–145 |
L (14-16) | 81–86 | 71–76 | 86–91 | 148–158 |
How to measure
Bust
Measure around the fullest part of the bust.
Waist
Measure around the natural waistline.
Hip
Measure around the fullest part of the hip.
Men's Tennis Footwear
| US | 7 | 7.5 | 8 | 8.5 | 9 | 9.5 | 10 | 10.5 | 11 | 11.5 | 12 | 12.5 | 13 | 14 |
| UK | 6.5 | 7 | 7.5 | 8 | 8.5 | 9 | 9.5 | 10 | 10.5 | 11 | 11.5 | 12 | 12.5 | 13.5 |
| EU | 40 | 40 2/3 | 41 1/3 | 42 | 42 2/3 | 43 1/3 | 44 | 44 2/3 | 45 1/3 | 46 | 46 2/3 | 47 1/3 | 48 | 49 1/3 |
| INCH | 9.84 | 10 | 10.23 | 10.43 | 10.62 | 10.82 | 11.02 | 11.22 | 11.41 | 11.61 | 11.81 | 12 | 12.2 | 12.59 |
| US | 7 | 7.5 | 8 | 8.5 | 9 | 9.5 | 10 | 10.5 | 11 | 11.5 | 12 | 12.5 | 13 | 14 |
| UK | 6.5 | 7 | 7.5 | 8 | 8.5 | 9 | 9.5 | 10 | 10.5 | 11 | 11.5 | 12 | 12.5 | 13.5 |
| EU | 40 | 40 2/3 | 41 1/3 | 42 | 42 2/3 | 43 1/3 | 44 | 44 2/3 | 45 1/3 | 46 | 46 2/3 | 47 1/3 | 48 | 49 1/3 |
| CM | 25 | 25.5 | 26 | 26.5 | 27 | 27.5 | 28 | 28.5 | 29 | 29.5 | 30 | 30.5 | 31 | 32 |
Women's Tennis Footwear
| US | 5.5 | 6 | 6.5 | 7 | 7.5 | 8 | 8.5 | 9 | 9.5 | 10 | 11 |
| UK | 3.5 | 4 | 4.5 | 5 | 5.5 | 6 | 6.5 | 7 | 7.5 | 8 | 9 |
| EU | 36 ⅓ | 37 | 37 ⅔ | 38 ⅓ | 39 | 39 ⅔ | 40 ⅓ | 41 | 41 ⅓ | 42 | 43 ⅓ |
| INCH | 8.66 | 8.85 | 9.05 | 9.25 | 9.44 | 9.64 | 9.84 | 10 | 10.23 | 10.43 | 10.82 |
| US | 5.5 | 6 | 6.5 | 7 | 7.5 | 8 | 8.5 | 9 | 9.5 | 10 | 11 |
| UK | 3.5 | 4 | 4.5 | 5 | 5.5 | 6 | 6.5 | 7 | 7.5 | 8 | 9 |
| EU | 36 ⅓ | 37 | 37 ⅔ | 38 ⅓ | 39 | 39 ⅔ | 40 ⅓ | 41 | 41 ⅓ | 42 | 43 ⅓ |
| CM | 22 | 22.5 | 23 | 23.5 | 24 | 24.5 | 25 | 25.5 | 26 | 26.5 | 27.5 |
Junior Tennis Footwear
| US | 1 | 2 | 3 | 4 | 5 | 6 |
| UK | 13.5 | 1.5 | 2.5 | 3.5 | 4.5 | 5.5 |
| EU | 32 ⅔ | 34 | 35 ⅓ | 36.5 | 37 ⅔ | 39 |
| INCH | 7.67 | 7.99 | 8.3 | 8.66 | 9.05 | 9.44 |
| US | 1 | 2 | 3 | 4 | 5 | 6 |
| UK | 13.5 | 1.5 | 2.5 | 3.5 | 4.5 | 5.5 |
| EU | 32 ⅔ | 34 | 35 ⅓ | 36.5 | 37 ⅔ | 39 |
| CM | 19.5 | 20.3 | 21.1 | 22 | 23 | 24 |
Unisex - Footwear Conversion Chart
| US (Men's) | 4 | 4.5 | 5 | 5.5 | 6 | 6.5 | 7 | 7.5 | 8 | 8.5 | 9 | 9.5 | 10 | 10.5 | 11 | 11.5 | 12 | 12.5 | 13 | 14 |
| US (Women's) | 5.5 | 6 | 6.5 | 7 | 7.5 | 8 | 8.5 | 9 | 9.5 | 10 | 10.5 | 11 | 11.5 | 12 | 12.5 | 13 | 13.5 | 14 | 14.5 | 15.5 |
| UK | 3.5 | 4 | 4.5 | 5 | 5.5 | 6 | 6.5 | 7 | 7.5 | 8 | 8.5 | 9 | 9.5 | 10 | 10.5 | 11 | 11.5 | 12 | 12.5 | 13.5 |
| EUR | 36 ⅓ | 37 | 37 ⅔ | 38 ⅓ | 39 | 39 ⅔ | 40 ⅓ | 41 | 41 ⅓ | 42 | 42 ⅔ | 43 ⅓ | 44 | 44 ⅔ | 45 ⅓ | 46 | 46 ⅔ | 47 ⅓ | 48 | 49 ⅓ |
| US (Men's) | 4 | 4.5 | 5 | 5.5 | 6 | 6.5 | 7 | 7.5 | 8 | 8.5 | 9 | 9.5 | 10 | 10.5 | 11 | 11.5 | 12 | 12.5 | 13 | 14 |
| US (Women's) | 5.5 | 6 | 6.5 | 7 | 7.5 | 8 | 8.5 | 9 | 9.5 | 10 | 10.5 | 11 | 11.5 | 12 | 12.5 | 13 | 13.5 | 14 | 14.5 | 15.5 |
| UK | 3.5 | 4 | 4.5 | 5 | 5.5 | 6 | 6.5 | 7 | 7.5 | 8 | 8.5 | 9 | 9.5 | 10 | 10.5 | 11 | 11.5 | 12 | 12.5 | 13.5 |
| EUR | 36 ⅓ | 37 | 37 ⅔ | 38 ⅓ | 39 | 39 ⅔ | 40 ⅓ | 41 | 41 ⅓ | 42 | 42 ⅔ | 43 ⅓ | 44 | 44 ⅔ | 45 ⅓ | 46 | 46 ⅔ | 47 ⅓ | 48 | 49 ⅓ |
Socks
| SIZE | MENS | WOMENS |
| SMALL | 4 - 6 | |
| MEDIUM | 6 - 8 | 6 - 10 |
| LARGE | 8 - 10 | 10 - 13 |
