Seals, gaskets, and o-rings are small, but a failed one can stop a tool, a vehicle, or an air rifle cold. The shopping decision comes down to a fork: solve one specific leak or build a stock of spares. One option is a $5.75 seal set for a precise air-gun valve. The other is a $35.99 large metric o-ring kit. Both are new, but they serve very different jobs.
Quick verdict
If you own a QB78, QB78 Deluxe, TH78, XS78 or another '78' model with a piercing tube cap, the direct seal set is the fix you need. If you want one kit to cover many future metric repairs, the ZDBB set is the broader buy. The choice is about whether you need a precise replacement or a versatile inventory.
Comparison at a glance
| QB78 Piercing Cap Seals | ZDBB 1,540-Piece O-Ring Kit | |
|---|---|---|
| Price | USD 5.75 | USD 35.99 |
| What you get | Two urethane seals (part numbers #3401 and #0409) | 1,540 nitrile rubber o-rings in 32 sizes |
| Material | Urethane | Nitrile rubber |
| Best for | Direct replacement on QB78-family air guns | General metric repair and maintenance |
Where each product wins
The QB78 seals win when you know the exact part. This set matches the factory-installed piercing cap/valve seals, so it is the right replacement for that valve. The material is tough, with good tear and abrasion resistance, so it holds up in a part that handles repeated pressure. They are made in the United States, but the real advantage is the exact fit for a specific application.
The ZDBB kit wins when you are facing unknown future jobs. With a broad range of metric sizes, it covers many common seals. The rubber resists oil, fuel, water, and wear, which suits automotive, plumbing, pressure washer, air, gas, and hydraulic uses. The included picks make removal and installation easier, and the storage case keeps sizes organized.
Product notes
QB78, QB78D, XS78, TH78 Piercing Cap & Valve TWO (2) O-Ring Seals URETHANE
This listing is for a matched pair of urethane seals from the piercing cap/valve area of the QB78-family air guns. The part numbers #3401 and #0409 are both shown in the owner's manual, but the seals themselves are identical and interchangeable. They fit the QB78, QB78 Deluxe, TH78, XS78 and any variant built on the '78' model with a piercing tube cap. Urethane gives the seals a real strength advantage, especially for tear and abrasion resistance, which matters in a part that has to hold up under repeated use. The limitation is that this set is built for that specific repair. If you aren't working on one of those air guns, these seals won't do anything for you.
ZDBB 1540pc Metric O Ring Kit 32 Sizes Nitrile Rubber Seals with 4 Picks Set
This is the opposite philosophy: instead of one exact seal, you get a wide metric assortment. The kit contains 1,540 nitrile rubber o-rings in 32 popular metric sizes, plus a four-piece pick set and a storage case. The material handles oil, fuel, water, and wear well, so the rings are suited to automotive, plumbing, pressure washer, air, gas, and hydraulic maintenance. The strength of this set is its breadth, covering common sizes before you even know you need them. The limitation is that an assortment can't guarantee the exact size you need; with a fixed set of 32 sizes, you may still have to source a special o-ring elsewhere. At over a thousand pieces, this kit is also a bigger investment in space and organization than a single replacement set.
Final choice by use case
If you have a QB78, QB78 Deluxe, TH78, or XS78 with a piercing tube cap and need that cap or valve sealed again, the targeted seal set is the right call. If you want to be ready for all kinds of metric o-ring repairs around the house, garage, or shop, the ZDBB assortment is the more useful long-term buy.
