Colgate believes it's what's on the inside that counts, which is why the Eco Spring Ultra II boasts an exceptionally high quality spring unit made of 150 coils of extra thick 13.5 - gauge tempered steel and 9.0 - gauge border rods for extra support. (colgatekids.com)
This mattress also includes deluxe spring unit has 104 thick, 13.5 gauge tempered steel coils, as well as 9.0 gauge steel border rods for extra edge support, firmness and durability. (colgatekids.com)
This mini crib mattress is a 50 - coil mattress, durable with a tempered steel spring unit for added firmness. (get-your-baby-to-sleep.com)