When you need seals gaskets o rings, the first thing to settle is whether you want a direct replacement for one specific assembly or a versatile stash for many repair jobs. On one side is a small replacement set made for the QB78, QB78D, XS78, and TH78 piercing cap/valve. On the other is a large rubber assortment in metric sizes for plumbing, automotive, and general repair work. The right pick depends on the job in front of you.
Quick Verdict
If you are repairing a 78-series piercing cap or valve, the specific replacement set at USD 5.75 is the direct buy. It gives you the seals your owner's manual calls out, and they provide strength plus tear and abrasion resistance. If you want broad coverage, the 400-piece assortment at USD 12.74 offers a much wider range of sizes for multiple repair tasks. Choose the focused set when you know the exact assembly; choose the assortment when you want to be ready for whatever comes next.
At a Glance
| Product | Price | What stands out | Relative price |
|---|---|---|---|
| QB78, QB78D, XS78,TH78 Piercing Cap & Valve TWO (2) O-Ring Seals URETHANE | USD 5.75 | Two urethane seals for 78-series piercing cap/valve assemblies | |
| O-Ring Assortment Kit 400Pc Nitrile Rubber Metric Sizes Industrial Seals | USD 12.74 | 400-piece nitrile kit with metric sizes from 4mm to 30mm |
Where Each Product Wins
The focused 78-series set wins when you need a precise fit for a piercing cap/valve repair. It is small, specific, and the lower-priced option here. The metric assortment wins when you need size variety across multiple projects; the resealable labeled storage keeps the rings organized and ready to use.
Product Notes
#### QB78, QB78D, XS78,TH78 Piercing Cap & Valve TWO (2) O-Ring Seals URETHANE
This set is built around one job: replacing the piercing cap/valve o-rings on QB78, QB78 Deluxe, TH78, XS78, and related 78-series models. It includes the #3401 and #0409 urethane seals, which are identical and interchangeable even though the owner's manual shows two part numbers. Urethane gives them strength and tear and abrasion resistance, so they can handle the repeated contact that a piercing cap makes. If your repair is on that specific assembly, this is the practical choice because you already have the right part without sorting through a kit. The trade-off is scope: this is a focused replacement set for one type of valve, not a general o-ring supply. If your project covers other equipment, you will need a different source of sizes.
#### O-Ring Assortment Kit 400Pc Nitrile Rubber Metric Sizes Industrial Seals
This kit is the multi-project option. The black nitrile rubber rings are soft and flexible, with a snap-on design for straightforward installation, and they come in a resealable labeled box that keeps sizes separated. Nitrile brings oil resistance, heat resistance, UV resistance, and wear resistance, which makes these rings a strong everyday choice for plumbing, automotive, and general repair tasks. The assortment covers metric outside diameters from 4mm to 30mm, with thickness options of 1mm, 1.5mm, 1.9mm, 2.4mm, and 3.1mm, so you can match a variety of glands. The limitation is that you are responsible for picking the correct ring from the kit. If you need a pre-identified seal for a specific piercing cap/valve assembly, the 78-series set is the more direct route.
Final Choice by Use Case
If you have a 78-series piercing cap/valve on the bench, the focused seal set is the right call. If you are stocking up for general maintenance, the metric o-ring kit gives you better long-term coverage. Match the part to the project, and you will have the correct seal when you need it.
