Post Box Springs with Flexible Arms 55 x 29 x 13 x 13.5 mm and 54 x 29 x 13 x 14.5 mm for Traditional Billboards

Size 1: The spring has an outer diameter of 7.5mm and an inner diameter of 5.1mm. The unfolded arm measures 55 x 29 x 13 x 13.5 mm and the wire diameter is 1.2 mm. Suitable for rods up to 4.5mm in diameter (the diameter of the spring decreases when the envelope flap is opened).Size 2: The spool is more compact, with an outer diameter of 7 mm, an inner diameter of 4.5 mm, unfolded dimensions of 54 to 29 to 13 to 14.5 mm and a wire diameter of 1.2 mm. Suitable for rods up to 4mm in diameter (the diameter of the coil decreases when the envelope is opened).High-carbon steel wire with surface anti-rust treatment is not easy to deform after repeated opening and closing, and it can return to position accurately even if there are many letters.Easy to install, no modification is required, directly replace the old spring, so that the mailbox door can open and close smoothly, silently and effortlessly.Mailbox spring with arm, including 2 sizes, convenient for replacement or upgrade of the complete set.-