This robust 25163160 insulator box is manufactured to OEM specifications for Mack SS34‑38, SS44‑SWS573 Camelback suspension systems with 4‑inch leaf springs, interchangeable with part number 52QK418BP5, constructed from heavy‑strength cast steel to bear heavy payload loads, effectively absorbs road shock and vibration, maintains proper leaf‑spring positioning and axle alignment, prevents abnormal suspension noise, premature spring wear and component shifting under harsh operating conditions, features precision‑drilled mounting holes for simple bolt‑on installation, it is a reliable aftermarket suspension repair part for fleets and service shops to restore stable handling and extend the service life of the whole suspension assembly.