An object literal of additional marker cluster options, that comply with the Marker Clusterer Google Maps JavaScript Library.<br>The syntax should respect the javascript object notation (json) format.<br>As suggested in the field placeholder, always use double quotes (") both for the indexes and the string values.<br><u>Hint:</u> it is possible to define the "imagePath" property to point the folder where are stored custom 1.png, 2.png, etc. marker clusters icons, such as: "imagePath":"\/themes\/custom\/THEMENAME\/images\/"