The ornamental design for a single drum roller, as shown and described.
FIG. 1 is a front right perspective view of a single drum roller showing our new design;
FIG. 2 is a rear right perspective view of the invention of FIG. 1;
FIG. 3 is a rear left perspective view of the invention of FIG. 1;
FIG. 4 is a front left perspective view of the invention of FIG. 1;
FIG. 5 is a right side elevation view of the invention of FIG. 1;
FIG. 6 is a left side elevation view of the invention of FIG. 1;
FIG. 7 is a front elevation view of the invention of FIG. 1;
FIG. 8 is a rear elevation view of the invention of FIG. 1;
FIG. 9 is a top plan view of the invention of FIG. 1; and,
FIG. 10 is a bottom plan view of the invention of FIG. 1.
The broken dash lines comprise claim boundaries. Neither the portions inside of the broken dash lines nor the broken dash lines themselves forms any part of the claimed invention.