These came from Riber but to be honest they are a common Chinese made Seat used by many brands. There are two straps going forwards that do all the real work and 2 going back that help to hold the back up whilst sitting down. There are two stiffening bars sewn into back of seat. Since I took photos I have used clips for another purpose but you can just feed straps through the eyelets. These were used for a demo event so hardly any signs of wear . Ideal for use with most sit on tops
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