When a seal fails, you have two very different ways to respond. If the failed part is the piercing cap or valve seal on a QB78, QB78 Deluxe, TH78, or XS78 air gun, you can buy a two-pack of the exact replacement seals and be done. If you'd rather never be caught without an O-ring again, you can grab a large assortment that covers cars, motorcycles, boats, faucets, pumps, and more. The real question is whether you need one perfect replacement or a box full of options.
Quick Verdict
If you own one of the "78" based air guns with a piercing tube cap, the two-pack of seals is the straightforward fix: it includes two identical replacements for a low listed price. If your goal is to handle O-ring needs across multiple vehicles and household repairs, the universal kit is the broader play.
Price & Scope at a Glance
| Product | Listed Price | Price Bar | Best For |
|---|---|---|---|
| QB78 Piercing Cap & Valve Urethane O-Ring Seals | USD 5.75 | Direct replacement for QB78-style piercing cap/valve seals | |
| Universal O-Ring Kit | USD 11.99 | General-purpose O-ring assortment for multiple repair jobs |
Where the QB78 Seal Pair Wins
This set is built for one job: the piercing cap and valve seals on QB78, QB78 Deluxe, TH78, and XS78 models. Both seals are identical factory parts, and they work across variants and calibers that use a piercing tube cap. The seal material is chosen for strength, tear, and abrasion resistance. If you need to stop a leak at that specific point, there is no sorting through sizes - you get the two seals and install one or both.
Where the Universal Kit Wins
The kit is the opposite strategy. It gives you a broad selection of O-rings, covering the sizes you're likely to encounter around the house, garage, or shop. It's made for cars, high-pressure washers, motorcycles, boats, pumps, solenoid valves, meters, and sensors, and the organizer helps keep the assortment sorted for the next time.
Product Notes
QB78 Piercing Cap & Valve Urethane O-Ring Seals
The strongest reason to pick this $5.75 set is precision: the two urethane seals are the exact style used in the QB78, QB78 Deluxe, TH78, and XS78 piercing cap/valve assembly. The parts carry part numbers #3401 and #0409 in the manual but are identical and interchangeable, so you're covered whether you need one now or a spare later. Urethane brings strength, tear resistance, and abrasion resistance to the seal, which matters in a part that sees repeated compression. The limitation is scope. This isn't a general O-ring assortment; it's for a specific piercing cap application. If your repair list includes faucets, pumps, or multiple vehicles, this two-pack won't help those jobs.
Universal O-Ring Kit
The kit earns its $11.99 price with volume and versatility. Its 1,050 O-rings are organized in a labeled plastic case, making it easy to find the size you need rather than digging through loose rings. The NBR material is rated for -40°F to 248°F, and the intended uses include faucets, high-pressure washers, motorcycles, boats, car engines, pumps, solenoid valves, meters, and sensors. That broad compatibility is the main strength. The limitation is that it's not tailored to any specific model. If you need the exact piercing cap seal for a QB78-style air gun, you'll be looking through the assortment rather than reaching for a part designed for that cap.
Final Choice by Use Case
Choose the two-pack if you have a QB78, QB78 Deluxe, TH78, or XS78 and the piercing cap/valve seal needs replacing. It's a small, focused purchase that gives you the matching replacement part for the job.
Choose the universal kit if you want one O-ring supply for many different repairs and you're willing to sort through sizes when the need comes up. It's the better fit for general maintenance across cars, water equipment, and household items.
