1.   Atheism for Marxism is not an optional extra or a mere facet but the very essence of it.

2.   Cruising chutes and Windsurfers are available as optional extras on some yachts.

3.   Etiquette and good manners are not a middle-class pastime or an optional extra for nice people.

4.   Leather seats are an optional extra.

5.   Made to measure in glass fibre with toughened glass roof and sides, optional extras include ventilation and double glazing.

6.   Most of the systems offer optional extras.

7.   Theories are not optional extras in science.

8.   This can be fitted with push release toggle as an optional extra.

9.   Tinted windows and a sunroof are optional extras.

10.   No, sorry, massager is an optional extra.