Innovative Hidden Bolt Design: the trolley assembly rollers boast a hidden bolt design, ensuring bolts are seamlessly recessed into the fastening channel; This design ensures smooth operation by preventing blockages Quality Construction: crafted from quality galvanized steel, the 4 wheel trolley assembly roller is designed to withstand and provide long-term durability; It's a reliable choice for challenging environments, ensuring your equipment remains robust and dependable over time Wide Compatibility for Versatile Use: equipped with silent M10 bolts and two nuts, this trolley assembly is compatible with 1-5/8" wide and all 1-5/8" or taller strut channels; It promises flexibility, catering to diverse applications with ease, whether in industrial settings or residential construction projects Enhanced Bearing Protection: featuring a raised section for bearing protection, this strut channel trolley significantly extends the lifespan of the bearings; By shielding them from direct impacts, it maintains consistent, reliable performance, reducing maintenance needs and enhancing overall efficiency Adaptable for Applications: whether applied as barn door rollers, replacement sliding door rollers, or garage door rollers, this strut channel trolley offers a versatile solution Color: As Shown Material: Metal Package Contents: 4*measurement wheel Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.