The ornamental design for a line-transfer device, as shown and described.
FIG. 1 is perspective view of a line-transfer device showing my new design;
FIG. 2 is a top plan view of the line-transfer device;
FIG. 3 is a bottom view of the line-transfer device;
FIG. 4 is a front elevational view of the line-transfer device;
FIG. 5 is a rear elevational view of the line-transfer device;
FIG. 6 is a right end elevational view of the line-transfer device; and,
FIG. 7 is a left end elevational view of the line-transfer device.
The broken line showing a carpenter's pencil in FIG. 1 is intended for the purpose of illustrating environment, and forms no part of the claimed design.