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How to measure a Grip Ring Stem.

Grip Ring Stem The Grip Ring Stem is the most popular stem used on office chairs and chairs with metal bases. The metal base normally would have a steel tube welded into the ends of the legs. The caster stem is inserted into that tube. Although most chairs require a 7/16" diameter stem, some need a 3/8" diameter stem.

CautionIf ordering a 3/8" Grip Ring Stem, please verify your measurements. 95% of all customer returns are 3/8" Grip Ring Stems where the customer measured incorrectly and really needed 7/16". You may even get a phone call or an email from us to verify your measurements. It's costly for you to have to exchange casters due to a measuring error.

How does it work?
The Grip Ring is just that. It Grips the sides of the tube when it is inserted. Also called an Expansion Ring or Friction Ring, the ring compresses as it is inserted into the tube. It is the friction of the ring against the side of the tube that holds the caster onto the chair. The position of the ring within the tube does not matter. It does not line up with a slot or groove. It is the friction that holds it on. This is why a shorter stem can be used as a replacement. If your stem is longer than 7/8" ( the typical length of a replacement stem ) our caster will work fine. The only important thing is that the depth of the hole be at least as deep as the "Length of the Stem" so that the stem does not bottom out in the hole. You can use a pencil to stick into the hole to check the depth.

Master Caster and some other companies use the following letters to describe these stems:
"B" Stem is 7/16" x 7/8" Long
"K" Stem is 3/8" x 1" Long

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Measuring Tips & Tricks
These are some Typical Stem measurements. Some people have a hard time using a ruler so here is how the measurements will look. 7/16" & 3/8 are very popular sizes for GRIP RING STEMS. 5/16" is the normal size for a GRIP NECK STEM however a BED CASTER STEM will probably measure 3/8".
Drill Bit
Use drill bits or other known size round devices to measure the size of a hole diameter or the hole depth.
Adjustable Wrench
It is very difficult to measure a round opject. Here is a tip to use an adjustable wrench to create 2 parallel edges the same size as the diameter of the "stem". Measure the width of the parallel edges and that would be the diameter of the "stem".
Open end wrenches are great measuring tools. Try the 5/16" to measure the base of a GRIP NECK STEM and try the 3/8" or 7/16" on a GRIP RING STEM. There should be a "slight" wiggle when using this method.
Sometimes it's easier to measure the hole if you're having a hard time trying to measure the stem diameter. This is also the correct method for measuring the hole for a socket used with a GRIP NECK STEM.
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