This product is either discontinued or we cannot get that from suppliers.
Intel Enhanced Value Rail Kit AXXELVRAIL, Works for all 438mm wide Intel 1U, 2U, 4U Rack Chassis, Rail allows adjustment within 609.6mm ~ 765mm to fit difference depth rack, Maximum extension when installed (travel distance) 424.2mm.
Works for 438mm wide Intel 2U/4U Rack Chassis and System families (H2000, R2000LH/R2000LT Swan Peak 2U, P4000M/P4000L/ P4000L-WS).