Mortise locks used with double doors having either rabbeted or astragal joints, must have fronts of corresponding sectional form. To avoid the extra cost of special patterns, the edges, or joints, of such doors should conform to established lock standards. The standard rabbet, or step, in the edge of doors is ½ inch, and the standard astragal joint has a ¾-inch bead. The proper bevel of a door, if any is needed, is determined by the size of butt and the width of the door, as shown in Fig. 137. The inner corner of the door travels on a radius with the center at the center of the pin of the butt, and must have a clearance to swing free of the jamb casing. This may be obtained by beveling the edge of the door, or, if its edge is left square, by leaving sufficient clearance between the door and its jamb. If the door is of fair width and the butt does not need to be very wide to clear the trim, it will be found that a square edge may be used without resorting to an unduly open joint, thus permitting the use of locks with regular front; that is, not beveled. [Illustration: FIG. 137] SHUTTER HARDWARE =97. Shutter Fasteners, or Adjusters.=—The most convenient fastener for shutters, or blinds, is the _Zimmerman_, or _Walling, type_, as shown in Fig. 138. These fasteners or adjusters secure the shutter in the closed, the open, and several intermediate positions, and are made both japanned and galvanized. They can be used with all styles of hinges, although they are generally combined with regular butts or with the New York blind hinge. [Illustration: FIG. 138] [Illustration: FIG. 139] =98. Shutter Rings.=—In Fig. 139 is shown a =shutter ring=. Rings should always be used on solid shutters to close them; the shutter being solid, furnishes in itself no edge which can be clasped in closing, which is not the case with slatted blinds. These shutter rings are tinned or galvanized to prevent rusting, although they may also be obtained japanned. A better type of shutter ring is that having an eye riveted to a plate, which in turn is attached to the shutter with several screws. =99. Shutter Bolts.=—Bolts are used for securing both slatted and solid shutters, but are chiefly intended for the solid shutter, which is used for protection. Shutter bolts are made of wrought steel in various sizes, from 6 to 16 inches long, and are to be had either japanned or galvanized. While the same shutter bolts are used on slatted blinds for keeping the blinds in a closed position, they afford little protection, as they can usually be operated through the slats. Common types of shutter bolts are illustrated in Fig. 140. At (_a_) is shown the ordinary wrought-steel shutter bolt, while the one shown at (_b_) is practically the same bolt with a lock attachment at _a_.