The number of chopper-building custom shops multiplied, as did the number of suppliers of ready-made chopper parts. According to the taste and purse of the owner, chop shops would build high handle bars, or later Ed Roth's Wild Child designed stretched, narrowed, and raked front forks. Shops also custom built exhaust pipes and many of the aftermarket kits followed in the late 1960s into the 1970s. Laws required (and in many locales still do) a retention fixture for the passenger, so vertical backrests called sissy bars became a popular installation, often sticking up higher than the rider's head.