Patent ID: 7428770

Claim:
A fastener comprising: a first side; a second side opposite the first side, the first side connected to the second side thereby forming a U-shaped structure having a cavity between the first side and the second side; a bottom portion wherein the first side and the second side are connected; a first engagement spring having a first surface connected to the first side in the vicinity of the bottom portion; a second engagement spring having a second surface connected to the second side in the vicinity of the bottom portion; and wherein at least one of the engagement springs comprises an engagement region comprising a hindrance portion, the hindrance portion comprising one structure selected from: ripple, uninterrupted elongated rib on the hindrance portion extending outside said hindrance portion, opening within the hindrance portion, said opening being accompanied by an upward solid bent, and a combination thereof; and wherein at least one of the first and second side comprises at least one barb comprising a bent front end with respect to said barb.