BCup Holder Expander Insert Cup Holder Extender Insert. Enlarge the size of your cup holder. Insert fits in most cup holders and improves their funtion by carrying large size drinks better. Catch basin holds spills and drips away from your drink. ReviewbP PP Cup Holder Expander Insert Cup Holder Extender Insert. Enlarge the size of your cup holder. Insert fits in most cup holders and improves their funtion by carrying large size drinks better. Catch basin holds spills and drips away from your drink.