I asked Professional Players if they use a 3U or 4U Badminton Racket! - YouTube
Kawasaki King K9 3u badminton racket 2020 range | badminton racket review
Amazon.com : YAKS 4PCS 3U Full Carbon Professional Ultra Light High Elastic Adult Student Training Badminton Racket Set Durable Type Blue-White : Sports & Outdoors
Amazon.com : YAKS 4PCS 3U Full Carbon Professional Ultra Light High Elastic Adult Student Training Badminton Racket Set Durable Type Blue-White : Sports & Outdoors