Downstem Sizing & Measurement Guide

Understanding Downstem Compatibility

Every TAG beaker or straight tube that uses a removable downstem follows the same precision-fit system — a male joint on the downstem that fits into the female joint on the water pipe.
While connection sizing is standardized (such as 18/14MM or 28/18MM), the downstem length can vary slightly because each TAG piece is handmade.

To ensure a perfect fit, you’ll need to know two key measurements:

1. Joint Connection Type (Size)

2. Downstem Insert Length

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1️⃣ Joint Connection Type (Size)

TAG downstems are identified by two numbers — for example, 18/14MM or 28/18MM.

These numbers represent the connection sizes on each end of the downstem — not diameter measurements.
Glass joints are precision-ground with a standard taper fit, forming an airtight seal when connected.

• First Number → The outer joint size that connects to your beaker or straight tube.

• Second Number → The inner joint size that accepts your slide, ash catcher, or accessory.

Example:
An 18/14MM downstem fits into an 18MM joint on your beaker and accepts a 14MM male slide.

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Common Downstem Configurations

Rule of Thumb:

• The first number = beaker connection size.

• The second number = slide connection size.

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2️⃣ Common Misunderstanding

Most TAG beakers feature an 18MM connection and use an 18/14MM downstem.
Because the slide that fits inside is 14MM male, customers often assume they need a 14MM downstem — but that’s incorrect.

✅ If your slide is 14MM male, you need an 18/14MM downstem.
❌ A “14MM downstem” will not fit your beaker.

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3️⃣ How to Measure Downstem Length

Downstem length is measured by the insert length, not the total length.
Measure only the portion that sits inside your beaker, from the bottom edge of the frosted joint to the tip of the stem.

Steps:

1. Remove and clean your downstem.

2. Measure from the end of the frosted joint to the bottom tip.

3. Round to the nearest ¼ inch (0.25").

4. The tip should sit roughly ¼"–½" above the base of the beaker’s bottom chamber.

Example:
If your downstem measures 4.00", that’s the size to select when ordering a replacement.

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4️⃣ Visual References

18/14MM Downstem

(18MM male outer joint → 14MM female inner joint)

28/18MM Downstem

(28MM male outer joint → 18MM female inner joint)

 

14/10MM Downstem

(14MM male outer joint → 10MM female inner joint)

 

18/18MM Downstem

(18MM male outer joint → 18MM female inner joint)

 

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5️⃣ Joint Close-Up

 

Outer Joint (Male) → Connects to your beaker.
Inner Joint (Female) → Accepts your slide or accessory.
Length → Measured from the end of the frosted joint to the end of the stem.

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6️⃣ Angle Doesn’t Matter for Downstems

• Downstems insert vertically — angle is not a factor.

• Angles (45° or 60°) only apply to ash catchers or adapters, not downstems.

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7️⃣ Handmade Fit Variations

Each TAG piece is handcrafted, so downstem fitment can vary slightly between units (±¼–½ inch).
Always measure your existing downstem before ordering a replacement — even if it’s the same model.

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Need Help Finding the Right Fit?

Email info@thickassglass.com and include the following details:

• A clear photo of your beaker or straight tube

• Joint size (18MM, 28MM, etc.)

• Measured insert length

• Your original TAG order number (if this is for a TAG product)

We’ll review your information and confirm the correct sizing before you place your order.

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Quick Reference Table

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Summary

• Measure insert length only, not total length.

• The first number = beaker connection size.

• The second number = slide connection size.

• Always measure before ordering.