LittoKid's products are manufactured to meet or exceed ASTM safety standards (ASTM F-1169). Assembly All litto kids cribs requires some assembly, and detailed instructions are included. Please follow each steps of assembly carefully. Two (2) person can easily assemble the cribs in less than 40 minutes. Crib Mattress Our cribs will accept any standard-sized crib mattress 52"L x 28"W x 6"H.