Pens and Pencils | Reviews and Data

Fisher AG7 vs CH4 Space Pen: What’s the Difference?

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Are you trying to choose between the Fisher AG7 and CH4 space pens? They look so much alike, but there are some differences in shape and price that makes then quite different when in use. So how do you choose? This article will help you tell the difference between these two pens and to find that one that’s right for you.


Have no doubt about it, these two are Fisher’s iconic pens. They are the ones people associate with the space missions, the ones that — as story would have it — cost millions of dollars to develop when the Russians just used a pencil. That story, as many of us know, has been debunked, but it’s still an amusing anecdote. NASA tells us that about 400 pens were bought from Fisher at $6 each for Project Apollo.

US3285228 Anti-Gravity Pen Patent

History of the Fisher Space Pens

The AG7 pen was patented in 1966 by Paul C. Fisher of Fisher Pens as the Anti-Gravity pen (hence “AG”). It was sent along with the Apollo 7 space mission in 1968 after over a year of testing by NASA. It is covered in US patent 3285228A, as the “Anti-Gravity Pen”, which was filed on May, 19, 1965 and granted on November 15, 1966. The patent covers the pen, as seen in the image, but the technology that really mattered was a commercially viable pressurized ballpoint cartridge.

The CH4 didn’t come along until 1981. The Chrome Plated Shuttle Space Pen became, and still is, the standard space pen used by NASA. It was first used by the Space Shuttle Columbia (STS-1) on April 12, 1981, heralding a new era of space exploration. It’s been used on every (manned) space mission ever since.

That’s a highly truncated history, but the point is this: the AG7 is the original space pen while the CH4 is a newer model that still manages to have excellent space credentials.

AG7 vs CH4: The Big Differences

  • The AG7 has an aggressive taper where the CH4 is practically straight from top to bottom
  • The AG7 has a cleaner “click” action and a slightly better built quality
  • The AG7 is heavier 23.8g vs 19.5g (when empty)
  • The AG7 has a nicer clip, made especially for the pen where the CH4 has a cheaper stamped clip

AG7 vs CH4: What’s The Same

Despite some notable differences, a lot of the qualities of these pens are the same.

  • Both use Fisher’s PR4 pressurized refill
  • Both are made of chrome-plated brass
  • Both are made in the USA
  • Both are “guaranteed against all manufacturing defects” and covered by Fisher’s excellent support services

Which Should You Get?

The AG7 is the true space pen and the space pen you want to have in your pocket when someone says, “Is that Space Pen?” but it’s more expensive then the CH4. The AG7 is also top-heavy which means it can feel inaccurate and isn’t always the favorite pen of all users. Here at Unsharpen we prefer teh CH4 for its more modern profile, cheaper price, and more balanced design.

That said, the click of the AG7 is magnificent and the look is classic, so it really makes a statement on your desk. It’s just a bit let enjoyable to write with when compared to the CH4.