The Spiral is made of elastomer embedded with silver ions, which lend the material antimicrobial properties, similar to some sportwear that is treated with silver ions to reduce odor. That said, it is important to keep in mind that this does not make the sleeve safe to share, it just means that your 3D might last a little longer and be less likely to develop an odor. The elastomer is soft, squishy, and quite stretchable. The material has only a very faint, non-offensive powdery odor. The sleeve is not tacky; however, it does leave a trace amount of oily reside on your fingers if you squeeze the material extensively.
The interior of the sleeve is completely smooth and offers a light sensation. However, inverting the sleeve reveals the true nature of the Spiral, a much more intense texture. Though stroking with the smooth texture is the best use of that side, the spiral side may be too intense for vigorous stroking.
The appearance of the 3D Spiral is revolutionary. Much like how Fleshlight broke new ground in discreet masturbator design, the 3D series embarks on a new form factor for sleeves. Realizing that a discreet masturbator can be much more than just a bland stretchy cylinder with an opening, Tenga went for a modern and exciting, yet functional form. The Spiral has the presence of a small sculpture, which is only enhanced by the semi-gloss black pedestal upon which the sleeve rests. Though I don't generally leave it out when company is over, I honestly feel that the Spiral is passable as decor; unless it is picked up and inspected, no one would be the wiser that the Spiral occasionally rests on your cock instead of its pedestal.
The Spiral is sized well. Short enough to be easy to handle, the Spiral is also able to accommodate a range of lengths, as the material is quite stretchy. Though I'm a bit longer than the sleeve, there was no discomfort since the material stretches as needed. The entrance hole is fairly small (smaller in diameter than a dime), but the material in this area is actually thinner, and thus more easily stretched. The suppleness of the entrance made entry easy; I was able to insert myself into the sleeve without having to use an extra hand to guide the head in. Once in, the toy was pleasantly tight-fitting, without being constrictive.
Depending on how you have the sleeve turned, the Spiral can be moderately or highly-stimulating. Using the smooth side, stroking is fairly low intensity, though squeezing out the air from the sleeve adds some suction that enhances the quality and degree of sensation. Stroking with the spiral side is very intense and was actually a bit too much for me to enjoy for an extended period of time. I am, however, more sensitive as I'm uncut.
After some experimentation with the spiral side, I found that my favorite way to use it was not to use it in the traditional stroking manner. Instead, I found that the spiral gives a wonderful sensation when it is rotated about one's cock. My preferred method is to insert myself into the lubed Spiral, then hold it between my palms and slide my hands back and forth (relative to each other). This effectively rotates the sleeve, allowing for the spirals to twist around all parts of the penis. The sensation was less directed, and thus less intense than thrusting, but much more pleasurable. It's literally enough to make my eyes roll back when I cum.
As this is a one-piece sleeve without a vent, the Spiral can be a bit noisy, depending on how you are using it. Stroking with the smooth side seems to make the most noise, a moderate "squish squish squish". The rotation method with the spiral side is considerably quieter.
The reversible design of the 3D Spiral makes cleanup easy. Unlike other mastubators that are not reversible, with the 3D series one is able to ensure that all fluids are rinsed away after use. After finishing with the Spiral, you hold it under running water while reversing the sleeve back to its storage configuration (spiral size out). Tenga's included directions do not specify to use soap, but a mild soap is generally OK for use with elastomer, so it shouldn't cause any problems with your Spiral. Keep in mind that the material cannot be sterilized, so sharing isn't advised. Once the Spiral has been rinsed clean, shake out the water and place it halfway down on its stand to air dry. Once completely dry inside, the sleeve can be pushed down on the stand, the clear cover replaced, and the ensemble can be stored.
Though elastomer can generally be used with both water-based and silicone lubricants, it seems that Tenga's material is not compatible with silicone lubes. In a guide to another Tenga product, the manufacturer states that they use a silicone-containing elastomer that precludes use with silicone lubes. I was unable to find any information regarding the exact material compatibility of the 3D series, but I would play it safe and stick to water-based lubes.
The packaging is excellent. As mentioned earlier, the stand and cover that contain the 3D Spiral make it look like a gallery-worthy sculpture. The base of the stand cleverly holds the instructions, as well as a sample of lube. Users should be aware that there are pieces on the stand that are used for shipping. Make sure you remove these before use, as one is a plastic piece that might be stuck in the sleeve. Please reference the instruction manual to identify which pieces must be removed.
Though the 3D Spiral is certainly worthy of displaying, do so with caution. Tenga warns that the material may discolor with exposure to sunlight, so it's probably best to store away from direct light.
The product instructions also state that with "correct use", the 3D Spiral can be expected to last about 50 uses. My expectation is that after repeatedly inverting the sleeve to use it, the material will begin to tear.