Materials and construction EN 397 Clause 4.1 External vertical distance EN 397 Clause 4.2 Internal vertical distance EN 397 Clause 4.3 Internal vertical space EN 397 Clause 4.4 Horizontal Distance EN 397 Clause 4.5 Height of use EN 397 Clause 4.6 Harness EN 397 Clause 4.7.1 cradle EN 397 Clause 4.7.2 Sweat band EN 397 Clause 4.7.3 Chin strap EN 397 Clause 4.8 Ventilation EN 397 Clause 4.9 Accessories EN 397 Clause 4.10 Impact absorption EN 397 Clause 6.6 Resistance to penetration EN 397 Clause 6.7 Pre-conditioning low Tª EN 397 Clause 6.2.3 Pre-conditioning high Tª EN 397 Clause 6.2.4 Pre-conditioning water immersion EN 397 Clause 6.2.5 Pre-conditioning artificial aging EN 397 Clause 6.2.6 Resistance to flame EN 397 Clause 6.8 Chinstrap Anchoring EN 397 Clause 6.9 PH EN ISO 3071