How to Close a 300LB Grip Trainer


First of all – can it be done? Is it even possible to close a 300lb (136kg) grip strengthener in your hand?

The short answer: of course it is!

The long answer: it takes years of grip training.

One of our long-time customers, Kenneth Brook, has managed the incredible and has successfully closed our RPM Power® 300lb Metal Series Gripper. Kenneth has generously answered our questions about how one can even go about achieving such a feat and offers his advice on how to close a 300lb grip strengthener.

increase hand strength, grip strengthener


Grip Strengtheners can come in many forms. Alone in the RPM Power store, we offer 27 different types of grip strengthening equipment, so you can imagine the variety that’s out there.

Grip trainers are generally smaller items that demand movement from the hand and fingers to get them going. By return, the grip trainer will build strength in the hand leading to a more powerful grip.

People use grip strengtheners for lots of different reasons. From grip-based sports like golf, tennis and martial arts; to rehabilitation and general fitness – grip training devices are something everyone should use to increase hand strength and maintain good hand health.



Metal Series Power Gripper

280Hz Autostart Powerball Pro

Finger Trumpet

Adjustable Power Gripper

Power Gripper Hand Ring

Finger Stretcher


If your goal is to crush a 300lb (or higher!) grip strengthener like Kenneth – or maybe you’re just starting out on your grip training adventure, it’s all about just one thing: practice, practice, practice.

If you’re new to grip training and aren’t sure which grip strengthener to start out with, we recommend always starting with a grip training device that you can only close marginally. When choosing a grip strengthener, many people will go for one that they can already somewhat close. This is fine for a short period, but what happens when you can quickly close the gripper fully after training for only a few weeks? You have to buy another.

You’re better off starting with a grip trainer that you can only close marginally – this way you’ll be able to spend more time building up grip endurance and strength through daily practice. Even if the gripper seems like an uncloseable beast at first, don’t worry. Give it a squeeze every day and soon you’ll start to notice progress.

We include a booklet containing some practical grip strength exercises with all RPM Power Grip Strengtheners. You can also download the online version on our info page here.


hand grip strength, increase hand strength
rpm power gripper, metal gripper

You’re better off buying a gripper that you can close marginally, rather than one which you can already close a little bit.


We were lucky enough to chat to Kenneth Brook, one of RPM Power’s longtime customers, who managed to close our 300lb Metal Grip Strengthener. With regular practice and some of his innovative homemade fitness tools, Ken is now able to crush this gripper – and he’s not stopping there:

How often do you use a grip strengthener to train your grip?

Once a day usually, but it depends if I’m doing a gym session. If I’m going to the gym, I’ll usually do some grip work afterwards. Although recently I have been concentrating on exercising other areas of the body and the forearms have been given a rest for a while now.

how to close grip strengthener

What kind of exercises or movements do you practice with your gripper and for how long?

In general, I warm up with a lighter grip trainer using only two fingers – either the top two or bottom two independently. Then I’ll do some closes: both with the gripper the right way up and upside down (which I find to be the more difficult position). 

This type of grip training usually takes me about 15-20 minutes. Recently though it’s been tough to find the motivation do some training, however with this blog post, I feel like this will reinvigorate my enthusiasm to close the 350lb Grip Strengthener!

In addition to grip strengtheners, I also use other grip training equipment, which I made myself at home. Some examples of pieces I use are:

  • A bit of wood with a rope on it, which winds weights up and down
  • Metal pinch block
  • Metal pinch hub
  • Wooden pinch block
captains of crush grip trainer close 300lb
close captains of crush 300lb gripper
hand grip trainer, rpm power gripper
The rope with weights on it is a simple grip training device that can also be bought.
It’s a wooden pole cut down to size with a rope threaded through it. I put weights on the other end and I put a squat rack pad on the barbell while it is on the squat rack. Resting my arms on the pad, I then wind the weights up and down until my forearms are begging for mercy.

When did you start using grip trainers to build hand strength?

I started using grip training devices when I was in my twenties – now I’m almost forty. I lost interest for a while, but then I recently got talking to Rory, (the boss of RPM Power) about how Brexit has stalled shipping and we started chatting about my grip strength and Powerball scores.

How long can you usually hold the 300lb gripper closed for?

I can hold it closed for a good 6-7 seconds.

grip exercise tool

Why do you enjoy grip training? Did you start for any particular reason?

I like that its a niche market of the gym world and, when it comes down to it, I have a good grip, which probably helped my interest. When I used to play floorball as a  goalkeeper, I would use a grip strengthener to help me warm my hands up. I have a few achievements for floorball and won the league two years in a row with my team. During that time I also won best floorball keeper in Scotland.

What will you do once you've closed a 350lb gripper?

I don’t think there is any way to top that! 


Kenneth estimates that he should be able to close the 350lb Metal Grip Strengthener in approx. 6 months time! Ken – we’ll be waiting for your update and in the meantime, good luck with your training.