There are two sizes of reference head-form for the non-optical tests described in the preceding clauses.The medium head-form approximates a 50th percentile adult male. The small head-form approximates a 60thpercentile, 12 year old child.The nominal dimensions are shown in Figure 11; the constructional details are given below and in the notes to thefigure.Where reference is made in this standard to a head-form specified in this clause, the size of head-form (medium orsmall) to be used, shall be that which is appropriate to the eye protector being assessed.Unless otherwise specified by the manufacturer of the eye protector, the medium size head-form shall be used.The appropriateness of the head form specified for the eye protector shall be confirmed by the test house.