The weight of hammers sold in the market is fixed. We will prepare multiple hammers to meet different needs. The hammer head is made of alloy steel. During production, it is necessary to melt and mix a variety of metals and then process them with different processes to obtain different characteristics. The entire production process consumes a lot of energy and releases a lot of carbon emissions. Sara Jane's hammer handle has a movable counterweight slider. By changing the position of the counterweight, the weight of the hammer head can be adjusted to meet the needs of use.