Rail fastener and method of producing the same, and double fastener

A rail fastener comprising:

• a first fastener stringer including a first attachment sheet and a first mating portion;
• and
• a second fastener stringer including a second attachment sheet and a second mating portion, the first and second mating portions being mated to form a rail portion, wherein
• the first attachment sheet includes a flexible first reinforcement sheet and a first skin portion, the first skin portion consisting of a same resin as the first mating portion and extending from the first mating portion so as to cover the first reinforcement sheet at least partially,
• the second attachment sheet includes a flexible second reinforcement sheet and a second skin portion, the second skin portion consisting of a same resin as the second mating portion and extending from the second mating portion so as to cover the second reinforcement sheet at least partially, and
• the first and second mating portions are configured such that when the first and second mating portions are mated, a first contact surface of the first skin portion or the first mating portion and a second contact surface of the second skin portion or the second mating portion are brought into a pressure contact with each other at a location between the first and second reinforcement sheets, the first contact surface positioned outwardly of sheet than an inner edge of the first reinforcement sheet, and the second contact surface positioned outwardly of sheet than an inner edge of the second reinforcement sheet.