Among lubricants, silicone based lubricants are considered some of the most luxurious available. And among silicone based lubricants, Pjur lubricants are considered some of the best. Their Back Door formula is no exception. The first two Back Door ingredients are the silicone: Dimethicone, Dimethiconol. Dimethicone is the densest of the liquid silicones and is also more expensive as a raw ingredient. This means that the Back Door formula should be on the thicker end of silicone lubricants. The other two ingredients: Jojoba seed oil, and Amyris balsamifera bark oil are added for their relaxing properties to help ease anal entry. More information on these ingredients can be found in these Ezine articles: Amyris Balsamifera Jojoba.
So, clearly Pjur specifically formulated Back Door for anal use. Since it is a silicone based lubricant, it is water resistant, which makes it particularly useful in the shower or the bath tub. It can also be used for vaginal sex, but the attributes of the extra ingredients may not be as helpful here. It might help in the case of a "first-timer" though. Circumstances where this lubricant may not work well are for a hand job or male masturbation as the relaxing attributes might not lead to a favorable result. Use with silicone toys should probably be avoided as well.

The silicone content of this lube is designed to make it one of the thickest silicone lubes. There are water based lubes available that use thickeners to make them even thicker than this, but those ingredients are not as body safe as this is. It is easy to forget that since silicone lube does not absorb into the skin, not as much lube is required to get the same degree of lubrication. A little dab seems like it won't last, but then you can just keep rubbing your fingers together and it never really goes away. The texture is smooth and not stringy, and doesn't get sticky over time. In fact, if you don't wipe/wash it off, you may find you can still feel it between your cheeks much later.

Silicone lubes generally don't have taste or odor due to the nature of the ingredients. One might think that the other ingredients may add some kind of odor or taste to the lube, but the jojoba oil is supposed to be odorless and tasteless. The bark ingredient, does seem to add just a hint of a "nutty" flavor to the lube. It doesn't taste bad or distracting, just not completely tasteless. It does seem to be odorless, however. If one is concerned about the ingestion of silicone lube ingredients, Metis Black's "got lube? (part 2)" article is a good read. This, of course, does not mention the other ingredients, so additional research is necessary for those.

The added ingredients in Pjur Back Door definitely provide this lube with relaxing properties. It worked very well in its intended anal application. It's effect on the sphincter wasn't all that noticeable, but it worked very well as a lubricant and seemed to reduce blood flow to the area very well. This would probably be a good lube to try with a large anal toy to see if it allows for easier entry.

Pjur Back Door comes in pretty simple packaging. Unscrew the cap and squeeze it into your hand or directly to the area that needs lube. A pump top to make acquisition from the bottle easier would be nice, but isn't all that common.

We used this lube both in and out of the shower. Its lubrication properties were very good. In fact, I would say it is probably the best silicone lube I have experienced from purely a lubrication standpoint. If Pjur products are all that good, I'll have to pick up some others. The additional ingredients seemed to do their job well - maybe too well in some cases.
We didn't seem to notice it too much during the anal activities, but when it was applied liberally to my penis it made it more difficult to obtain an erection. It was kind of an interesting feeling, as I still had most of the sensation but I just wasn't really getting hard. I will do further tests with a large glass butt plug and provide a follow up review with the results.
This product is a high quality lube with some interesting additional features that might make anal play a little more comfortable. If you have had trouble with anal activities in the past, this might be something to try.