This cock ring is pretty straight forward. They are supposed to be tight enough to reduce circulation so that your erection is firmer and to prolong time to ejaculation. The small ring goes around the shaft and the large one goes behind the testicles. The nub is placed to provide your partner with stimulation to her clitoris. The spikes are there to provide stimulation to her labia. It is all put together in a compact package so it is easy to hide and/or travel with. There are no mechanical parts so it can be used where ever you are. Although the material has some give, it isn't too stretchy so it performs its primary function well. It is not quite as comfortable as some other rigid cock rings that are out there and it can pull hairs as it goes on and comes off.

The Nubby Dual Ringer is made out of rubber. Rubber isn't the safest of materials out there, but this isn't a penetrative toy, so that is not as big of a concern. If you or your partner has a latex allergy, then you will want to avoid this one. The texture of the rubber is matte and it tends to be a little grabby (think thick, round rubber band), so a little bit of water or silicone based lube aids in making the processes of getting it on and off more comfortable.
As far as texture is concerned, the nub and spikes certainly add something to the experience. My partner reported that in a a missionary position she could feel it on her clitoris and in a doggy style position she could feel the nub on her rectum. It was neither bothersome nor overly stimulating, but she said she could definitely feel it. Some cock rings are just about doing their job so the Nubby Dual Ringer has more stimulation than that while others have a vibrator designed to hit the clitoris, and those can provide more stimulation. That means this one splits the difference between the two. Since this has no mechanical parts you can feel safe using it any where which can't necessarily be said for cock rings with vibrators.

According to the Nubby Dual Ringer product page the rings are 3/4" and 1" unstretched diameter. My personal measurements indicate 1" and 1+3/4". Measuring stretched diameters is a little trickier, but I feel that the 3" and 5" indicated on the product page are pretty accurate. This means that the rings are pretty stretchy and should fit most guys, but these rings require quite a bit of effort to stretch to these levels, so they provide quite a bit of resistance. This helps them do their job, but it can also make them uncomfortable. If you are well endowed or cannot handle a little discomfort from your cock ring, then you may want to look elsewhere.

Since the Nubby Dual Ringer is made out of rubber, cleaning is pretty simple, but it is porous. This means that there is no way to sterilize the Nubby Dual Ringer so it should not be shared with multiple partners. This shouldn't be a big problem because the cost is low enough that purchasing a new one after a change in relationship should not be a big issue if you like it enough. Regular cleaning can be accomplished with soap and warm water and then it can be patted dry. It's diminutive size makes storage simple. Just put it in a plastic bag or other storage pouch and it's good to go. Either water or silicone based lubricants are acceptable. Avoid petroleum based lube as it could degrade the material.

The Nubby Dual Ringer comes in plastic packaging meant for hanging. The toy is on full display so one can see the color and size before the purchase. The cardboard insert has a picture of a male torso on it, and although there is no nudity, I would still hesitate to call it discreet. I suppose that the packaging could be used for storage as it still can be closed after opening as long as you don't mind the extra space it takes up.

The first time we used this was in the shower. I was able to get it on easily enough although there was some discomfort as I got it placed properly. Once it was on, I definitely knew it was there as I could feel the pressure of the rings around my junk. My erection was quickly achieved and easily maintained. I did seem to last a little longer before ejaculation than usual. The pressure of the rings did introduce some discomfort that was a little distracting, but nothing that couldn't be ignored. The stretchiness of the rings made removal pretty easy as well. If not for the discomfort this ring would be pretty near perfect. If cock and ball torture is what you're after, then the Nubby Dual Ringer provides some of that. It certainly isn't the most extreme device available, but I think it should provide some discomfort for most guys, if that's what you're after.