FOUR LETTERS THAT CHANGES COURSES IN THEIR ORBIT

I may be under no obligation but for this one thing

I may be under no obligation but wilfully render

I may be under no obligation but graciously bestow as received

I may be under no obligation but choose to follow in revered footwear

I may be under no obligation but desirous to lighten 

I may be under no obligation but to pour salve to relief

I hope you enjoy your stocking and it brings a lasting smile to your face.

Hint: it has 15 distinct, lovely fillers that together make a glorious sound. Try not to be impatient, insisting not to have your way to open it immediately. You will be glad you did.