Image is related to a Jodo shu "Juzu" 浄土宗用
Jodo shu (Pure Land school) has four different kinds of juzu. One, for example, known as a hyakumanben is a huge 'communal' juzuused by the whole congregation who, sitting in a circle, all hold the juzu which is rotated in a clockwise direction, with each person passing the beads from their right hand to their left.
A second juzu, /Images above) is known as the nikka (or: rokumanben guri nikka) - designed for counting 60,000 recitations of the nembutsu - is shown here. This juzu consists of two loops - one loop with forty beads and a parent bead (called an oyadama); and one loop with twenty-seven beads interspaced with small beads and one oyadama.
This second loop has a floating metal ring to which two tassles are attached - one with ten flat beads; and one with six small round beads.    Please refer to  James Deacon's page Link button in terms to read carefully.

This is a Japanese wooden Buddhist prayer beads for ZEN (Soto Zen). Beads are made of natural woods. It's called "Juzu" in Japanese. This type of Juzu is used for Soto Zen. It has a metal ring.

Wearing Buddha beads reminds one to pay attention to one's daily actions. Reciting the Buddha's name signifies eliminating one's vexation. One can recite as many times as one wishes but the important thing is to focus while one is reciting. 

Buddhist prayer beads or malas (Sanskrit: mālā "garland") are a traditional tool used to count the number of times a mantra is recited, breaths while meditating. Juzu beads match sometimes different description and most of the times depends by the temple or eventually the priest.

The prayer beads are the Buddhist implement that helps common mortals advance in their Buddhist practice. (Seiten, p.970)

In Nichiren Shoshu for example, their prayer beads consist of two long strands joined at either end with two large beads. Hanging from the outside of these large beads are two shorter strands on one side, and three on the other. They are strung with white braided cords with white pompom tassels at the end. These sets of two and three strands are equidistant and opposite from each other. The two large beads are called the father and mother beads. Both of them represent the Buddha. Between the father and mother beads are 108 beads of a smaller size. These beads represent earthly desires. There are also four smaller beads. They are opposite each other, two being seven beads away from the end with two strands, and the other two are fourteen beads beyond the first two. These four small beads represent the four leaders of the Bodhisattvas of the Earth - Jogyo (Superior Practice), Muhengyo (Boundless Practice), Jougyo (Pure Practice), and Anryugyo (Unwavering Practice) - and also indicate the four virtues of the Buddha's life. These are eternity, tranquility, true self, and purity. Directly under the father bead, which is at the end with two tassels, is a smaller bead. This represents the essential nature of the Law, the eternal, absolute truth. Because of their profound significance, you should treat your prayer beads with respect, just as you would the Buddha. To understand the meaning of the beads is to begin to understand the profundity of Buddhism, the correct practice, and the reason for expressing gratitude to the Three Great Secret Laws and the three treasures. 

The Buddhist nenju or juzu (sometimes o-juzu) Nenju refers to the 'pearls used for conscious practice', and juzu means 'pearls to count' considered a protective spell against evil spirits.  Nenju are often given as gifts to celebrate a birth, marriage or given as memories as a source of protection for loved ones.

Nenju, treated with respect should not be left lying around nonchalantly, and should be kept clean and kept in good condition. When irreparable should be disposed  to a Shinto shrine, where, together with the old spells of good luck, they will be respectfully withdrawn by the priests.

There are also "informal" nenju commonly and they have different size and numbers of beads.

Styles of nenju:
Different Buddhist schools have slightly different styles of formal nenju. For example: