property Items.ItemHeight(Item as HITEM) as Long

Retrieves or sets the item's height.

Item as HITEM A long expression that indicates the item's handle. If the Item is 0, setting the ItemHeight property changes the height for all items. For instance, the ItemHeight(0) = 24, changes the height for all items to be 24 pixels wide.
Long A long value that indicates the item's height in pixels.

To change the default height of the item before inserting items to collection you can call DefaultItemHeight property of the control. The control supports items with different heights. When an item hosts an ActiveX control ( was previously created by the InsertControlItem property ), the ItemHeight property changes the height of contained ActiveX control. The CellSingleLine property specifies whether a cell displays its caption using multiple lines. The ItemHeight property has no effect, if the CellSingleLine property is False. If the CellSingleLine property is False, you can specify the maximum height for the item using the ItemMaxHeight property.   Use the ScrollBySingleLine property when using items with different heights. Use the ItemAllowSizing property to specify whether the user can resize the item at runtime. Use the Height property to specify the height of the bars.