Reviewing the "Inline Dual Action" by Grav Labs
Double joint designTwin perc, double cooling systemAwesome party piece
Not very portableExpensive Difficult, if not impossible to use alone
3.1Overall Score
Reader Rating 2 Votes

Price:              $270                       Manufacturer: Grav Labs
Made in:         USA                       Material: Borosilicate Glass
Height:            13″
Available in different colors: Yes – choice of decal color
Can add accessories: Yes

First Impressions

When the package arrived from Grav Labs we carefully removed all the protective wrapping to reveal a very serious looking piece of equipment. The Inline Dual Action from Grav Labs had arrived. Standing over a foot in height, it could be a sacred chalice sent from the future, or something that would be useful for DNA sequencing, but no. It’s a pipe, and now my friends, we are going to smoke it….

Inline DA


Immediately you understand that this is something special. When it is sat on the table in front of you, it is an intimidating sight, and you think perhaps you should be reaching for safety goggles rather than a grinder and a chunk of bud. The Inline Dual Action stands over 12 inches in height with a Grav decal running down the main chamber. The example we received came with the black decal but a range of colors are available. Starting from the bottom we have a thick, circular base supporting a horizontal, cylindrical chamber from which the other parts sprout. The horizontal chamber is divided into 3 sections: on the right, there is a female joint with a bowl for dry flower; on the left, a male joint with a dome and quartz nail for oils and concentrates. The central section houses the inline perc and runs up into the vertical chamber which sits on top. The vertical chamber likewise is divided into 3 sections;  the bottom, which also makes up the central section of the horizontal tube where the inline perc is positioned; the mid section, which takes up the bulk of the vertical tube and contains a second perc (this time a domed showerhead type) and the top, a narrower “neck” section which terminates in the mouthpiece. Grav Labs also include a glass stopper which can be used to close off either joint.


From a quality point of view, the first thing you notice when handling this piece is the weight. It is heavy, a good sign for a water pipe made entirely of glass. Low weight means low quality and this looks and feels very solid, which isn’t surprising considering Grav’s reputation for quality. All their pieces are constructed using the highest quality laboratory grade scientific glass and the Inline Dual Action illustrates once again the skill and craftsmanship Grav Labs possess. The glass is smooth and the whole thing shines when the sun catches it. The decals are crisp and add some color to an essentially transparent, albeit quite stunning chunk of glass. The joints and the stopper are well engineered and create a good, airtight seal. The slits in both percs were clean, sharp, and even. One of our testers commented that if bongs were required equipment in hospitals, then Grav would probably supply them.


First things first. Water. If weed is the fuel, then water is the oil that holds the whole bong experience together. We initially tried pouring cold water straight down the neck to fill the rig, but this didn’t work. The top chamber filled with water and none made its way to the bottom sections. So we started again. This time we removed the bowl from the female joint and carefully poured water in, until it had equalized across the 3 chambers, ensuring that the inline perc was properly submerged. We replaced the bowl and added water via the neck into the upper chamber, this time ensuring that the showerhead was underwater. It quickly became apparent that you need assistance when using this bong. It’s probably too big and heavy for most to reasonably hold whilst in use, and even when placed on a table, bowls still need lighting and dabs still need dabbin’. So unless you are blessed with eyes that operate independently of each other and you can look in two places at once, you are going to want at least one pal to hand with either dabber or ignition at the ready. The best configuration we came up with required the assistance of two friends. Set the rig on the table, ask one friend to heat the nail and dab the oil, whilst the other fires up the herb in the bowl. You can also use the stopper to block one side and just use the one joint if you so desire. But where’s the fun in that?!

Inline Dual Action Collage


Now, all you other pipes out there can be as big and brash as you want, but you’re going to have to work hard to match the formidable power of this inspired creation from Grav. With a full bowl of green on one side, and a healthy dab of concentrate on the other, this monster is a tester for even the most hardened bong hitters, and we seriously mixed it up for our test session. We packed the bowls with a heavy kush and added a fat dab of some delicious citrus-y, pure sativa shatter whenever we got halfway through the bowl and wow, this pipe did not disappoint. With the kush a-blaze, the real fun began.

As the smoke tumbled and swirled through the inline perc, up into the last and largest of the chambers, it was drawn through the showerhead perc to remove any unwanted particulates that might have made it past the inline perc. OK, that’s all fairly straightforward for any dual perc pipe, you might be thinking, but the key difference here is whilst you’re settling into the flow of smoke from the bowl, your pal has been heating that quartz nail just out of your field of vision and now you have the added benefit of freshly vaporized shatter mixing with, and eventually taking over, from the smoke from the bowl. Now whether that shatter vapor is a blessing or a curse will depend entirely on your abilities as a smoker/vaper. After hitting a fat bowl of herb, chasing it down with almost pure THC vapor can be a challenge, but if you are capable of rising to the occasion, then the rewards are clear. You are going to be extremely high.

Obviously when you’re being so greedy, there are inevitably going to be consequences, and some might say that trying to consume double hits is stupid. Yes, this pipe messes you up. Yes, it makes you attempt things that you know aren’t a good idea. BUT WE LOVED IT. Endless combination possibilities, fat bowls – little dabs, little bowls – fat dabs; dab-bowl-dab….. This went on for hours, our longest test session to date, and certainly one of the best. The Inline Dual Action is great fun and left us all in tatters. We highly recommend it. Every home should have one.

Ease to clean

Neither straightforward or quick, but with a little time and effort with the isopropyl alcohol it will come up like new even after the heaviest and oiliest of sessions.

The Good

  • Grav Labs quality
  • Double joint design
  • Twin perc, double cooling system
  • Huge but smooth hits
  • Hell of a party piece

The Bad

  • Expensive – it is good value for quality, but $270 is a lot of money
  • Very limited portability
  • Difficult, if not impossible, to use on your own

Should you buy it?

I don’t think this would be anybody’s only bong, but if you’re looking for the ultimate party pipe and can afford it, then yes, go for it. Even if you don’t use it too often yourself it will surely be fun putting your friends through their paces every now and again!