Choosing between a specialized o-ring seal made for one specific airgun and a massive multi-size assortment can feel like comparing a scalpel to a toolbox. In the seals, gaskets, and o-rings space, the right answer depends on whether you are finishing a single repair or stocking up for every future leak.
Quick Verdict
Pick the QB78, QB78D, XS78, and TH78 piercing cap & valve seal pair when you are servicing an airgun and want seals built for that piercing-tube cap setup. Pick the metric O-Ring Assortment Kit when you are handling a mix of car, faucet, air, and gas repairs and want multiple sizes close at hand.
At a Glance
| Option | Price | Price Bar | What You Get |
|---|---|---|---|
| QB78 Piercing Cap & Valve O-Ring Seals | $5.75 | White urethane seals for QB78, QB78D, XS78, TH78 and 78-based airguns | |
| 1050-Piece O-Ring Assortment Kit | $9.99 | 1050 nitrile-rubber o-rings in 21 metric sizes, 1mm to 25mm inner diameter |
Where Each Product Wins
The QB78 seal pair wins when you need a direct replacement for a 78-series airgun piercing cap. The seals, listed as #3401 and #0409 in the manual, are identical and interchangeable, so you get a spare right away. They are made in the United States.
The multi-size assortment wins when variety matters more than one perfect match. Its many metric sizes cover many common sealing jobs, and the organizer box with labeled compartments makes it easy to find the size you need. It also features wear resistance for frequent-fitting applications.
Product Notes
QB78 Piercing Cap & Valve O-Ring Seals
For $5.75, you get two white urethane o-ring seals. They are identical and interchangeable, so you have a backup even though the owner's manual lists two part numbers (#3401 and #0409). These fit the QB78, QB78 Deluxe, TH78, XS78, and other 78-based models that use a piercing tube cap. The urethane material provides superior strength, tear resistance, and abrasion resistance, and the seals are made in the United States. This is the simpler choice when you need to rebuild the piercing cap on a specific airgun and do not want to sort through a large assortment. For a faucet or gas fitting unrelated to a 78-series airgun, a broader o-ring kit would be more practical.
1050-Piece O-Ring Assortment Kit
The $9.99 kit packs 1050 o-rings into 21 metric sizes, with inner diameters from 1mm to 25mm and thicknesses from 1mm to 4mm. That range gives you a strong chance of finding a ring that fits a car repair, faucet, air, or gas fitting. They are made from commercial-grade nitrile rubber (NBR), so they resist oil, water, heat, and abrasion, and they operate from -40°F to 248°F. The plastic organizer box has separate compartments with size labels, making it easy to pick the right ring and store the rest. The wear resistance also helps in frequent handling. The trade-off is that you need to match the correct size to your groove; a specific QB78 piercing-cap repair may call for more careful measuring than a purpose-made pair would.
Final Choice by Use Case
If you are repairing a QB78, QB78 Deluxe, XS78, or TH78 piercing cap, the QB78 Piercing Cap & Valve seal pair is the no-guessing answer. If you want a broad o-ring stash for small repairs around the house, garage, or utility vehicle, the O-Ring Assortment Kit gives you far more coverage. Choose the precise pair for an exact fix, or the big kit for flexibility across many jobs.
