Weighing Out - Trainer Responsibilities

The trainer is responsible for making sure his horse carries the correct weight which includes both hood and blinkers (if these have been declared), number cloth, martingale, breastplate, saddle and fully dressed jockey.
Leads Weights May Be Added

Lead weights may be added to the jockey's saddle to give the correct weight.
Items Not Included
Crash helmet, whip, bridle, rings, plates or anything worn by the horse's legs are not included in the weight.
Things That Might Be Included

If a rider is weighed-out with hood or blinkers, the horse must wear them for the race.
Condition (or Allowance) Races
Condition (or allowance) Races: in which a basic weight allowance for age and sex of horse is varied by added weight penalties for past successes (measured in prize money terms).
Handicap Races:

Handicap races: in which the weights are adjusted to try to give horses an equal chance of winning.
In all steeplechase and hurdles, and in some flat races, weight allowances are given to apprentices and jockeys with limited winning experience, providing that the prize money involved is below a certain amount.