The ornamental design for an adjustable beltloopfasteningdevice, as shown and described.
FIG. 1 is a top perspective view of the new design for an adjustable belt loop fastening device;
FIG. 2 is a bottom perspective view thereof;
FIG. 3 is a top view thereof;
FIG. 4 is a bottom view thereof;
FIG. 5 is a right side view thereof, with the left side being a mirror image of the right side;
FIG. 6 is front view thereof, with the back view being the same as the front view; and,
FIG. 7 is a perspective view thereof, shown in a closed configuration in a position of use on two belt loops.
The broken line showing of a garment with belt loops in FIG. 7 depicts environmental subject matter that forms no part of the claimed design. The broken lines on the surface of the adjustable belt loop fastening device in FIGS. 1-4 and 7 depict portions of the article that form no part of the claimed design.