The first component we will observe is the actual ability to race.
Horse's with low numbers indicate they are at the top of the handicap, meaning although they carry more weight than the higher numbers, it is down to the fact they are 'better' or 'classier' horses.
However, having to carry big weight has proved a huge disadvantage in the past over this mouthwatering test of stamina and longevity.
Since 1978, 124 horses have tried to win with more than 11st 5lb on their back with just two winners – Many Clouds (11st 9lb) in 2015 & Neptune Collonges (11st 6lb) in 2012. 22 of the last 28 winners had carried 10st 12lb or less.
This year's big favourite Tiger Roll - who won with 10st 13lb last year, carries 11st 7lb this time around after Nigel Twiston-Davies withdrew Bristol De Mai, leaving Anibale Fly to top the field at 11st 10lb.
Regardless on the weight you carry, stamina is an absolute must when building up a national CV.
There are few races a season that can prepare the runners for this nail-biting four-and-a-quarter-mile steeplechase, and even individuals who do find a similar prep; you do not know how much it takes out of them.
The four-miler at Cheltenham usually bodes well, as does the Glenfarcas Cross Country Chase, along with the Peter Marsh at Haydock and the Classic Chase at Warwick.
Many do arrive off the back of a rehearsal over three miles indicating they want further. You have to go back to 1970 to find the last winner of the Grand National who had not previously won over three miles.
This race is a unique trip and plenty of the runners will fail to stay the distance, so finding a horse who will be strong towards the finish is absolutely crucial.
Eight of the last ten winners of the race had previously run over a trip of 3m3½f or further, with the only two exceptions being Many Clouds (2015) and Ballabriggs (2011), both of whom were owned by Trevor Hemmings, who has Lake View Lad and Vintage Clouds this time around.