FIELD Replacement Bottom Piston O-Ring 4.5 x 1.78 Urethane – Piston Seal

The high-pressure FIELD urethane O-ring (4.5 x 1.78 mm) is designed for the lower piston part of regulators. This small but critical component ensures precise pressure regulation and the airtightness of your gun.

  • Material: Premium urethane with high resistance to extreme pressure and mechanical stress.
  • Compatibility: Designed for FIELD regulators and other systems utilizing this standard piston size.
Availability In stock
Delivery to:
30.01.2026
Delivery options
Code: 18027E
0,91 € 0,75 € excl. VAT
FIELD Replacement Bottom Piston O-Ring 4.5 x 1.78 Urethane – Piston Seal

FIELD Bottom Piston O-Ring: The Key to Precise Pressure Regulation

The bottom piston O-ring plays a vital role in stabilizing the output pressure from your tank to the gun. While the top seal separates high pressure, the FIELD Replacement Bottom Piston O-Ring works at the very heart of the regulation mechanism. By using urethane instead of standard rubber, this ring better withstands shear stress and rapid temperature changes.

Proper function of this seal is essential for consistent muzzle velocity. If this ring is worn out, a "creeping" effect may occur, where the regulator pressure slowly rises above the set limit, which can be hazardous to your gun's internal mechanisms.

Key Features:

  • High Durability: Urethane material is extremely resistant to abrasion and chemicals found in lubricants.
  • Consistent Performance: Ensures smooth piston movement for stable firing without pressure fluctuations.
  • Long Lifespan: Designed for the demanding conditions of paintball and airsoft fields.
  • Easy Maintenance: Standardized size for quick replacement during regular servicing.

Technical Specifications:

  • Dimensions: 4.5 x 1.78 mm
  • Material: High-strength Urethane
  • Application: Lower part of HPA/CO2 regulator pistons

Frequently Asked Questions (FAQ)

Question: How do I know if the bottom piston O-ring is faulty?
Answer: If your gauge pressure slowly rises after a shot (creeping) or if the regulator fails to hold the set working pressure, this ring is the primary candidate for replacement.

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