introduction of artificial surfaces has changed the game. To take into account the specificities of this surface, new tactics and new techniques (such as the Indian dribble) have been developed and new rules have been introduced to control these new techniques. Regarding the evolution of the hockey player material, the sticks have changed shape, with the bent head at the bottom, which used to be about 15 centimetres long, becoming much stubbier. The extra length was no longer necessary, as the ball travelled much straighter on the flatter synthetic fields. The shorter length made playing the ball with the "backhand" (playing with the head of the stick to the player's left, with the head rotated 180 degrees from its usual position) much easier, increasing the speed with which this tactic, often used for evasive manoeuvres, could be used. It also makes trapping the ball by placing the entire stick on the ground, with the point of the head resting on the ground to the player's left, possible, and this stopping technique is now universal for trapping the ball at penalty corners. The sticks have also tended to become stiffer as to hit the ball harder. Fibreglass, carbon fibre and kevlar were first applied to the traditional wood core in the early 1970s. Sticks with an aluminium core have been produced but are now prohibited due to the danger they pose when broken. Wooden sticks are less and less common, and players are now playing with sticks entirely made of synthetic composite materials. The goalkeeper equipment has followed the same trend, becoming more and more able to resist to strength of the balls hit by these new generation sticks. Helmets have become compulsory, padding is thicker and of more shock-absorbing (and reflecting) foam material and more areas of the body are padded. The new equipment is very expensive and is often a considerable burden for clubs or individual goalkeepers to purchase. The composition of the hockey ball has also changed, from a leather ball with a seam similar to a cricket ball, to a seamless, usually dimpled hard plastic ball. These plastic balls are cheaper, more durable, more consistent in their behaviour, and are unaffected by water; a key requirement in water-moderated synthetic fields used in elite-level hockey. Ancillary player equipment has also changed. The studded boots for grass fields are banned (and were in any case very uncomfortable) on synthetics,