=Sash chains= are made in the form illustrated in Fig. 72, and may be had either in steel, red metal, or bronze. The sash chains in the market are usually made in four sizes, being numbered from 0 to 3. The makers, however, have no agreement regarding these standards, so that the numbering is not uniform; one manufacturer’s No. 0 chain may be his heaviest make, while a chain of the same number furnished by another maker may be the lightest chain that he manufactures. In order to provide against this discrepancy when specifying, it is well to name the maker of the chain. The lightest sash chain will support sashes weighing from 40 to 75 pounds, while the heaviest will carry sashes that weigh from 150 to 250 pounds. [Illustration: FIG. 72] [Illustration: FIG. 73] =63. Sash Balances.=—By the use of =sash balances=, one of which is shown in Fig. 73, there is no necessity for weight boxes, counterweights, etc. The contrivance illustrated has been manufactured for many years, and the original intention was to have it displace the sash pulley, cord, and weight for double-hung windows. Installing spring sash pulleys costs more than the older method of hanging by means of counterweights. They are constructed with a long, spiral spring enclosed by a drum, on which the tape _a_, Fig. 73, winds and thus raises the sash. The coil spring in this balance is made of either light or heavy material, according to the weight of the sash it is intended to counterbalance. They are seldom used, however, except where there is insufficient room for sash weights. The steel tape is liable to be twisted and broken by jarring in operating the sash, and for general use it has been found that the most positive action is secured by pulleys and weights.