Good quality, medium power, compact binoculars have been disappearing from the market over the last 10 yrs, so I was eager to try out the Pentax 6.5 X 21 Papillo binoculars. The first number refers to the magnification; the second number refers to the diameter of the objective lens in mm. The classic reference standard for binoculars is 7 X 50 submarine commander's glasses. Although manufacturers push "higher power is better", 7 times magnification is about the highest usable power with a hand-held pair of binoculars. Above that, the image is noticeable shaky, unless the binoculars are outfitted with image stabilization, or you use a tripod or other stand. A 50 mm objective gives great light-gathering ability if you view objects in dim light, but results in large, bulky, heavy units. A ~20 mm objective provides a good compromise between light-gathering ability and compactness. Note that for a fixed objective lens diameter, the image grows dimmer as the magnification increases. Not an issue in bright sun, but a factor to consider if you use binoculars to view concert performances or go on nature trips in the woods. Another good reason to opt for lower magnifications.
An unusual feature of this unit is the close-focus ability. Note that some reviews give the impression that it's practically a stereomicroscope ("focusses within inches!"); but this is not an accurate characterization. The manufacturer states 1.6 ft, which I verified (~19 inches from the front bumper). The coated optics are of good quality with flat uniform field, no noticeable color fringes, and no noticeable internal reflections. The two objective lenses are recessed into the body and covered with a flat window, which makes the unit easy to clean. The eyepieces have long eye relief (~distance between the eyepiece and your eye; in general, the longer, the better), suitable for use with eyeglasses. The retractable eyecups are one of the best designs I've come across. Typically a rollup rubber eyecup is used. If you don't wear glasses, you unroll the eyecup to full length to keep stray light from getting into your eyes. If you wear glasses, you roll the eyecup down so you can get your eye closer to the eyepiece. What usually happens is that the rubber cracks easily as it is rolled and unrolled (especially since the material is attacked by sweat and skin oil). In this unit, the eyecups are helically mounted. You adjust the extension by twisting it: there are three click stop positions. The eyecups are rubber coated to minimize scratching of eyeglasses. The right eyepiece has a diopter adjustment (in case your left eye and right eye have unequal vision, with or without eyeglasses).
Mechanically, the design is excellent. Bulkier than other compact designs, but that's a design tradeoff needed to accommodate the close focus range. Light weight and low cost are achieved with an all plastic body. Almost the entire body is coated with rubber, including a rubber bumper in the front of the unit. The rubber has just the right texture to provide a sure grip, even with sweaty hands. It doesn't feel too "goopy". The eyepieces swivel to adjust interpupillary distance (distance between your eyes). The center focus is smooth. The shape is unusual and takes some practice getting the right grip. But it works well. You cradle it in both hands. It provides a steady grip while allowing easy interpupillary adjustment and focussing. It has a tripod socket. Pentax sells an optional tripod adapter, a short pedestal to allow the body to clear the tripod platform. If you use a ball-and-socket head, the adapter is not needed. The socket is a standard 1/4-20 thread. Note that it is a plastic thread, so it is not very robust. With the 6.5 magnification, though, a tripod is not needed unless you are viewing for long times and your hands get tired.
Minor carps. The unit comes with a dual cover for the eyepieces. The cover falls off easily and is easy to lose, but there is a loop so you can tie it onto the neckstrap. There is no cover for the objective lens. This combo (eyepiece cover/no objective cover) seems to be common these days, but I don't understand why you would leave the objective lenses unprotected. The unit comes with a vinyl pouch. There is no separate neckstrap, but there are slots if you want to attach the pouch to a belt.
For the money, this unit is a good value and I'll give it 5 stars relative to its price point. Of course it won't match the optical quality of a $1500 Zeiss or Leitz, and don't expect to pass this down to your grandkids. Amazon price right now is a good deal, but the touted list price of ~$250 is well over the official list price on the Pentax website (~$130).