The ornamental design for an instrumentsupportholder, as shown and described.
FIG. 1 is a front view of an instrument support holder;
FIG. 2 is a rear view of the instrument support holder shown in FIG. 1;
FIG. 3 is a right side view of the instrument support holder shown in FIG. 1, with the support column extended, a left side view being the same but mirror-reversed;
FIG. 4 is the same side view of the instrument support holder as that shown in FIG. 1, however with the support column partially retracted, a left side view being the same but mirror-reversed;
FIG. 5 is a right side view of the instrument support holder like that shown in FIG. 3, however with an elongated pivot arm mounted on the support column, a left side view being the same but mirror-reversed;
FIG. 6 is a top view of the instrument support holder as shown in FIG. 2; and,
FIG. 7 is a bottom view of the instrument support holder as shown in FIG. 2.
The instrument support holder is used for mounting supports for instruments such as mobile telephones, had-held computers in postions convenient for the user.