Model NBR-6 Disk-style Retainers
The NBR-6 is another inexpensive line of retainers that are made of inert flexible nitrile rubber, also known as NBR or Buna-N (a material also commonly used in O-rings). Like the PCR-6, they are basically identical in shape and dimension to the Model SSR-6 and are capable of being inserted without stress in the same way (see the SSR-6 or the Order Page for details), but are rubbery and softer and have a certain amount of resilience and “give” which also allows them to be slightly compressed (round versions more easily than oval versions) during the insertion process and hence makes size selection less critical. Some users will no doubt take advantage of this rubbery softness and compressibility to maximize their retentive abilities by deliberately using a substantially larger French size than is possible when using a hard unyielding retainer like the SSR-6 or PCR-6. It can add significantly to their effectiveness, versatility and usefulness in demanding applications.
In particular, besides allowing use of larger sizes, this rubbery softness and resilience also makes the NBR-6 noticeably more comfortable than its hard unyielding counterparts when strong traction forces are applied. They tend to bend and distort into a more body conforming conical shape when put under load. But the trade-off is that their rubberiness may also possibly limit retentive ability in some instances. The holes of NBR-6 retainers can stretch, allowing spouts to pull thru and release from the NBR-6 if enough tensile force is applied. This is somewhat like a safety feature. However, the amount of force that can be applied before the spout pulls thru will depend on the size and shape of the retainer being used and other factors and is largely unpredictable (in fact, it might never even happen), so you should not rely on that alone for protection in case you ever accidentally apply too much force (such as if you were to drop a heavy attached weight, or slip and fall while your dick is attached to something).
Because of differing material shrinkage characteristics, the NBR-6 cannot generally be made from the same molds as other molded retainers like the PCR-6 and may not be available in all of the same size groups (because molds are expensive), but will, in the size groups that are available, have the same dimensions and be offered in the same sets of three (one round and two other progressively larger oval versions that all have the same critical French size). The only difference is that the NBR-6's holes are slightly smaller to provide a better seal against spouts. If you find that the holes are too tight to allow easy sliding of your spout, simply stretching them by hand or by inserting a tapered pen will usually be enough to provide a looser fit. Or you can ream them out slightly with the provided piece of wet sandpaper. Enlarging the holes to any greater degree, such as to fit a larger spout of your own making, is generally not recommended and should only be attempted with a small grinder bit attached to a high-speed rotary tool. Don't try to drill them out with a twist drill; you'll just mangle them.
Please refer to the Sizing Guidelines for basic information on how to select the right French size. If you select a French size that is significantly larger than your orifice, you do so at your own risk. Tether Products will not guarantee that they can be sufficiently compressed to fit in every instance. It will largely be a matter of intelligent guesswork and experimentation, and will depend on the sensitivity of your orifice and its size, as to how far the NBR-6 retainers can be oversized and still be comfortably inserted without distension. Retainers in the larger group sizes (especially the oval ones) tend to be much less compressible (relatively speaking) than the smaller sizes because the hole size is always the same, unless you enlarge the hole for a larger spout of your own making. To give you some idea of the leeway in fitting that the NBR-6 can afford, I have no difficulty whatsoever in quickly squeezing in a size 32Fr retainer, which would normally take some time and/or require some preparatory stretching and warm-up with a sizing sound and dilator if I was using a hard retainer like the SSR-6 or PCR-6.
ATTENTION: The NBR-6 retainers that are currently in stock regrettably do not meet Tether Products' normally high standards. In some cases they have a noticeable amount of "flash" or sharp ridges at their outside periphery where the molds mated, which could be a source of irritation and discomfort during use. It became a question of either finding a better supplier and waiting another 4 months or possibly longer for better stock to arrive, or accepting the shipments as-is. In the interest of time and to keep costs down, Tether Products chose the latter and is asking customers to remove any flash or sharp ridges (if they exist) themselves. A small piece of ultra-fine wet sandpaper and instructions are included with every set for this purpose.
