Endorsed & co-owned by Ken Griffey Jr.

Train the swing
everyone copied.

The PX 40/40 Power Extender. A wearable swing trainer for baseball, softball and golf.

What separates a legend's swing from yours?

It's not the bat.

It's not the stance.

It's extension.

Getting your arms all the way through the ball, every swing. The PX 40/40 trains it, rep after rep, until it's muscle memory.

How it works

Strap in. Set the tension. Swing.

  1. 01

    Slide on the sleeve

    The PX 40/40 arm sleeve goes on first. Add the comfort pads for a snug, personal fit.

  2. 02

    Strap in the trainer

    Line your elbow up with the elbow space in the trainer, then tighten the straps.

  3. 03

    Set your tension

    Press the button and pull the tension band to the resistance you want. Adjust any time.

  4. 04

    Swing and repeat

    Integrated cords respond as you move, guiding your arm into full extension, rep after rep.

Ken Griffey Jr. following through on a golf swing

The Kid · Hall of Famer

A generation copied Ken Griffey Jr.'s swing. Now he's helping you train yours.

Hall of Famer. The Kid. One of the most famous swings the game has ever seen. Ken Griffey Jr. endorses and co-owns PX 40/40.

Train like The Kid

Every hitter. Every age.

Young player at the plate, bat raised

Young hitters

Bad habits stick. So do good ones.

Kids learn a swing by repeating it. What they repeat is what they keep. Sized for players from age 6.

Softball player mid-swing

Softball

Built for softball too.

Same trainer, same extension. Choose softball at checkout, in black or white.

Ken Griffey Jr. swinging a golf driver

Golf

From the diamond to the fairway.

Does your lead arm break down at impact? It's called the chicken wing. The answer is extension: arms long through the ball.

Size guide

Find your fit.

9

→ Small

6101418+
S

Small

Ages 6–10

Your fit
M

Medium

Ages 11–14

Your fit
L

Large

Ages 15 and up

Your fit

The blueprint of legends. Now yours.

Black PX 40/40 trainer

In the box: PX 40/40 trainer, arm sleeve, comfort pads and adjustable tension bands

PX 40/40 Power Extender

$99.99

Free US shipping

In stock · Launch run of 3,000 units

Sport

Color

Size · Find your fit

Add to cart

Secure checkout with PayPal or Stripe

Real swings. No edits.

Show us your swing.

More on TikTok →
Live review Live review · part 1 On the range High school testimonial
  1. 1

    Post a clip with your PX 40/40: bat or club.

  2. 2

    Tag @px_4040 and #PX4040.

  3. 3

    We feature our favorites on @px_4040.

  4. Under 18? A parent or guardian posts for you.
Black PX 40/40 trainer

Coaches, teams & retailers

Training facilities, team orders and sporting goods stores: talk to us about wholesale pricing.

Wholesale & team orders

or email info@px4040.com

Buy now

PX 40/40 · $99.99 · Free US shipping