Hendrickson's ULTRAA-K 40K air slider axle suspension system for the van and refrigerated trailer markets. Building on proven VANTRAAX air slider design expertise, the ULTRAA-K system is engineered with an optimized strength-to-weight ratio, making it stronger than comparable standard and heavy-duty 40K slider models in the market today. It is the lightest slider system in the industry by nearly 100 lbs., according to the company.