Many Precor models do have a rear guard. Seen here: https://www.amazon.com/Precor-TRM-932i-Commercial-Treadmill/dp/B00DJ36YHI https://www.amazon.com/Precor-TRM

Many Precor models do have a rear guard. Seen here: https://www.amazon.com/Precor-TRM-932i-Commercial-Treadmill/dp/B00DJ36YHI https://www.amazon.com/Precor-TRM-932i-Commercial-Treadmill/... The roller/belt design also appears different - much smaller rollers and a smoother belt on Precor models. Not idea if that contributes, but it might.