Speedo Junior Fastskin LZR HyperPro Jammer Size Guide

This size guide covers the Speedo Fastskin LZR HyperPro Jammer — Boys' Junior, a World Aquatics approved competition racing jammer available in sizes 24–30 (ages 7–14). The LZR HyperPro delivers all-day comfort combined with moderate compression, engineered to work in synergy with the swimmer and built to last race after race. Designed for all ages, skill levels, strokes and distances.

Key features include comfortable compression engineered for comfort and performance, optimised seamlines and bonded dual layers designed and engineered for fit, flexibility and performance, a soft waistband with silicone gripper for easy comfortable fastening and a softer feel, and shape-retaining lightweight fabric with durable wrapped yarns and water repellant coating — built to last race after race. Fully approved by World Aquatics and developed by Speedo Aqualab. All measurements are body measurements taken from your child's body, not garment measurements.

Shop Kids Speedo Racing Jammers →

Body Measurement Points

How to Measure

To find the correct LZR HyperPro Jammer size, use a soft measuring tape and take measurements directly against your child's skin. Age is shown as a guide only — always use body measurements, as children develop at very different rates. Use the hip measurement as the primary guide.

A
HipMeasure around the fullest, widest part of the hips and seat, keeping the tape horizontal.
B
WaistMeasure 6cm below the narrowest part of the natural waist, keeping the tape level all the way around.

Note: Ages shown in the sizing table are a guide only. Always use body measurements to select the correct size. Children of the same age can vary significantly in size.

Sizing Table — Boys' Fastskin LZR HyperPro Jammer

	Size 24	Size 26	Size 28	Size 30
Age (guide only)	7–8 yrs	9–10 yrs	11–12 yrs	13–14 yrs
Body Measurements
Waist cm	61.0–64.0	65.0–69.0	70.0–74.0	75.0–77.0
Hip cm	70.0–74.5	75.0–79.0	80.0–83.0	84.0–87.0

Ages shown are a guide only. Always use body measurements to select the correct size. All measurements are body measurements, not garment measurements.

Fit Notes — Speedo Fastskin LZR HyperPro Jammer (Boys')

The LZR HyperPro Jammer uses moderate compression engineered for all-day comfort and performance — it will feel firmer than a training jammer but is designed to be worn comfortably throughout a full competition day, making it an excellent choice for junior swimmers at any level.
Always use body measurements to select the correct size — the age guide is indicative only, as children develop at very different rates.
If measurements fall across different size brackets, use the hip measurement as the primary guide, as the jammer needs to seat correctly over the hips before the waistband can sit flat.
The soft waistband with silicone gripper should sit flat and secure against the body with no roll or gap, providing all-day comfort throughout the competition day.
The suit should be completely wrinkle-free when correctly fitted. Any bunching or gathering indicates the suit is too large.
The bonded dual layers and optimised seamlines should lie flat against the skin with no rubbing or pressure points at any point during racing.
The leg hems should end above the knee in line with WA regulations and feel snug but not restrict movement or blood flow.
Allow 10–15 minutes to try on correctly for the first time. Take care with fingernails and jewellery when pulling on the suit to protect the water repellant coating.
Do not use petroleum-based products, oils, or creams before putting on the suit — these degrade the water repellant coating.
Rinse in cold fresh water immediately after each use. Do not tumble dry, iron, or dry-clean.
Unsure? Contact our team or call +44 1827 330600. Speak to a member of staff at Allens if you are unsure.

Frequently Asked Questions — Speedo Fastskin LZR HyperPro Jammer (Boys')

Yes. The Speedo Fastskin LZR HyperPro Jammer is fully approved by World Aquatics (WA) and is legal for use in all sanctioned competitive swimming events. It has been developed by Speedo Aqualab and is built to compete at all levels of the sport. Always check with your event organiser for any local age group rules regarding tech suits in competition.

The LZR HyperPro Junior Jammer is available in sizes 24 to 30, covering an approximate age range of 7 to 14 years. However, age is a guide only — always use body measurements to select the correct size, as children of the same age can vary significantly in size. If your child's measurements fall between two sizes, speak to a member of staff at Allens for guidance.

The LZR HyperPro sits within the Fastskin racing range and is designed to deliver all-day comfort with moderate compression, making it suitable for all skill levels, strokes and distances. It features optimised seamlines, bonded dual layers, and a soft waistband with silicone gripper — built to last race after race. It is engineered to work in synergy with the swimmer and developed by Speedo Aqualab for performance at every level.

Always select by body measurements. The age ranges shown are a guide only — children develop at very different rates and age alone is not a reliable indicator of the correct size. Measure the waist and hip and compare to the sizing table above, using the hip measurement as the primary guide. Speak to a member of staff at Allens if you are unsure.

The LZR HyperPro Jammer should feel firm and compressive but comfortable throughout a full competition day. The soft waistband with silicone gripper should sit flat with no roll, the bonded seamlines should lie flat with no rubbing, and the suit should be completely wrinkle-free when correctly fitted. The leg hems should sit above the knee in line with WA regulations.

The Speedo Fastskin LZR HyperPro Jammer is designed for all competitive swimming events and all four strokes. It is specifically engineered to suit all skill levels, strokes and distances — making it an ideal choice for junior swimmers competing at club, county, or regional level who want a reliable, comfortable racing jammer that performs race after race.

Yes. The LZR HyperPro Jammer's moderate compression and comfortable fit make it an excellent choice for a junior swimmer's first Fastskin racing suit. The soft waistband with silicone gripper makes it easier to put on and wear throughout a full competition day compared to higher compression suits, while still delivering the performance benefits of a World Aquatics approved racing jammer.

The LZR HyperPro Jammer is a competition racing suit and is not designed for regular training use. Using it for training will degrade the water repellant coating and shorten the lifespan of the suit. Reserve it for races and competition warm-ups to maintain its performance. Speedo offer a wide range of junior training jammers for everyday training use.

The LZR HyperPro uses a shape-retaining lightweight fabric with durable wrapped yarns and water repellant coating, specifically designed to maintain its performance properties race after race. Unlike some higher-compression Fastskin suits, the HyperPro is engineered with durability in mind for all levels of competition use — making it a reliable investment for junior competitive swimmers.

Rinse the suit thoroughly in cold fresh water immediately after every use to remove chlorine and salt. Do not machine wash, tumble dry, iron, or dry-clean. Store the suit flat and dry, away from direct sunlight. Avoid contact with sun cream or petroleum-based products as these degrade the water repellant coating. Regular care after each use is essential to maximise the lifespan of the suit.