This is an extension box for a Japanese honeybee hive, a stacked box type, with knots and cracks. It's for Honey's House and Honey's Mansion. Japanese honeybees prefer weathered boxes, so professionals sometimes prepare them a year in advance. The dimensions are: outer dimensions 33cm x 33cm, inner dimensions 27cm x 27cm, and height 15cm. The thickness is 3cm, providing a comfortable environment in the summer heat and winter cold. The comb support rods are made by shaving them down to 8mm. There are various ways to install the support rods, such as a cross or a well shape, but bees dislike too many, so we use two parallel rods. Therefore, when adding extension boxes, if the support rods in the lower box are horizontal, set the support rods in the upper box vertically. This way, you can achieve an effect similar to a well shape with fewer rods. During the honey harvesting season, the hive should be four or five tiers high, so one of them will be supporting the comb, and the comb will not fall even if you cut the upper tier. If you are using this for other hives, please be sure to understand the dimensions before purchasing. Please note that these are handmade, so there may be deviations of approximately ±2mm and deviations due to wood expansion and contraction. By the way, if a strong colony grows without problems, in the fall, we stack up to 5 or 6 tiers including the entrance box, so if you have a Honey's series set, we recommend purchasing 2 or 3 additional boxes.