Short answer. If your air pad came with a pump sack, or you sleep on foam, a Flextail pump adds weight for no gain. A pump sack is the lighter-or-equal route: Sea to Summit states 48 g for its Airstream pump sack, the same as the Zero Pump 2 with battery. Your lungs weigh nothing but have limits in the cold. Flextail's pump is the right buy for a pad with no pump sack and a brand the Airstream page does not list.
This page is for the backpacker who looks at a 48 g pump and asks if a simpler option does the same job. We read each maker's own product page on 2026-11-01. Rivals are named but not linked, because they are not what this page sells. We have not tested any of them.
The options, with each maker's own words and numbers
| Option | Stated weight | What its page says | When it is the better pick |
|---|---|---|---|
| Your lungs | 0 g (our label) | Therm-a-Rest's page says "Use a pump sack or breath to inflate your pad." Its page also says to "avoid breath inflating your self-inflating pad" in freezing conditions, because moisture from your breath can freeze inside. | Warm trips, and any pad you do not mind blowing up for a minute each night. |
| Sea to Summit Airstream Pump Sack | 48 g (1.7 oz) | Says it fits all Sea to Summit sleeping mats and "Inflates most Sea to Summit Air mats in only two to three compressions." It is a 20 L dry sack that can also hold clothes or a sleeping bag. | You own a Sea to Summit pad. It also does a second job, which can replace a dry sack. |
| The pump sack in the pad's box | Counted inside the pad weight | Therm-a-Rest lists a pump sack under "What's Included" for the NeoAir XLite NXT, 13 oz (370 g) regular, R-value 4.5. | You already own it. Do not buy a pump. |
| Foam pad (Z Lite SOL) | 14 oz (0.41 kg) regular, R-value 2.0 | No inflation. The page says it can be layered under another pad for added R-value and puncture protection. | Warm trips, or as a base layer in cold. The simplest answer, and it never loses air. |
| Flextail Zero Pump 2 | 48 g with battery (29 g without) | Maker says 6 nozzles cover "90% of sleeping pad brands", 45 seconds to inflate or deflate, and the battery is replaceable and rechargeable. | You own a pad with no pump sack, or from a brand the Airstream page does not list, and you will remember to charge it. |
The grams, in plain arithmetic
- Zero Pump 2 against the Airstream sack: 48 - 48 = 0 g difference on the stated figures. The Flextail pump needs a charge. The sack needs none.
- Foam pad against the NXT: 410 g against 370 g, so the foam pad is 40 g heavier (our arithmetic). It needs no pump. The NXT's 370 g already counts its pump sack as a box item, not as weight we add.
- Tiny Pump 3X against the Airstream sack: 67 - 48 = 19 g more, for 5 kPa, 300 L/min and a lamp, all maker figures.
What each source does not say
- The Airstream page lists fit for Sea to Summit mats only. It says nothing about pads from other brands.
- Flextail states no test of how many nozzle sets fit which pad valve. A reviewer on the Max Pump 3 page said the adapters did not lock onto their packraft valve.
- No page gives how many nights a charge lasts in cold weather.
- Neither Therm-a-Rest nor Sea to Summit says anything about Flextail, and we did not test them against each other.
The honest verdict
For most pads sold with a pump sack, the answer is "do not buy a pump". For a Sea to Summit pad, buy the sack, not the Flextail. For a pad with no pump sack and a valve a sack does not fit, a Flextail Zero Pump 2 is a fair swap at 48 g. Ask Flextail whether a nozzle fits your pad before you buy, and remember the warranty only covers gear bought from flextail.com (see what the pages say).
If the Flextail is the right answer for your pad
Our reason to click: its page states the weight both with and without the battery, so you can choose which figure to plan on.
We earn a small commission on qualifying sales, and 90% of it goes to charity (you can pick which); your price is unchanged. Full disclosure.
The Flextail links on this page are affiliate links. We earn a small commission on qualifying sales, and 90% of it goes to charity (you can pick which); your price is unchanged. Full disclosure.
Sources
- Sea to Summit Airstream Pump Sack product page (seatosummit.com/products/air-stream-dry-sack-pump, shown as text so it is not a link), read 2026-11-01.
- Therm-a-Rest NeoAir XLite NXT and Z Lite SOL product pages (cascadedesigns.com/products/..., shown as text), read 2026-11-01.
- Flextail Zero Pump 2, Tiny Pump 3X and Max Pump 3 product pages (flextail.com/products/..., shown as text), read 2026-11-01.