If you want to be a top class second row, you must not be scared of heights.
During a line out, you are up in the air a long way, around 13 feet off the ground, when you're catching a ball.
You're up in the air hundreds of times a week, so you need to have a lot of faith in the guys lifting you up there.
Ben Kay's facts
Born: 14 December 1975, Liverpool
Height: 6ft 6in
Weight: 17st 8lbs
Club: Leicester Tigers
Position: Second row
England debut: 2 Jun 2001 against Canada
I can't really think about if I'm going to land safely, all I'm thinking about is catching the ball coming in.
You need to have good hand-eye co-ordination to be a successful line out jumper.
Hookers tend to throw the ball in quite quickly, but you also have to deal with the opposition who'll be doing their best to put you off catching the ball.
You don't have to be tall to be a line out jumper, but it does help.
There aren't too many second rows under 6ft 4in in modern rugby now.
There was a time when the big guys were dominating, but those days are now gone.
If you're slightly shorter, you make up for your height with your speed across the field.
Leading the line out
You've got to have top notch communication skills.
When it comes to deciding who the ball is going to on your throw in a line out, the calls get quite complicated at international level.
Kay reaches for the ball against Wales
If the opposition know your line out calls, then your team will be going into a game where it's easy for your opponents to defend.
Some guys find it hard to learn the calls at the start of the week. There are plenty to learn and everyone needs to understand every single call.
It's my job as the leader of the line out to make sure everyone knows the calls.
I do this by discussing each call with all the other forwards, repeating them over and over.
Another thing I always do is study the opponent's line out.
I use video analysis and study their main jumper, their hooker, where they tend to throw when they're at different areas of the pitch.
I try to work out what their favourite tactic is then to try to read their movements.
A lot of what I do is about disguise. I try and con their hooker and jumper into thinking that I'm going do one thing, then doing the other.
But I owe a lot of my success down to the guys that help me most, the hookers, props and back row.