Regina 19/137ZRP Drive Chain Connecting Link (Zrp/Zrt Series 525Zrp Rivet) Z-ring chains feature the patented Z44 sealing rings, which greatly improve performance and wear life, making previous X-ring and Z-ring chains obsolete 50% reduction in friction compared to traditional O-rings Constant lubrication from special high-temperature grease in the critical pin/bushing area provides long life High-carbon alloy pins to minimize wear and increased roller thickness to prolong durability Thicker outer plates and quad-riveting for greater tensile strength