Yes. They are legal. "1 iron golf" system clubs do not normally mean using a single golf club to substitute for all irons normally used in the play of golf with a swivel head so that the angle of loft is changed. The term "1 iron golf" generally refers to a system where there are the normal number of irons in a set. However, the length of each club is the same, with only the angle of loft of the head of each club changing. The benefit is that the golfers swing never changes throughout the use of all of the irons in the golf set. The distance is controlled by the angle of the head of the club producing increasing loft as the club number goes up from 3,4,5,6,7,8,9 to the PW (pitching wedge.) The disadvantage of this system is that there is a small decrease in the distance that you can attain with the shorter club length. This would normally only be a problem with the 3 iron since this is used for the longest iron shots and therefore you, theoretically could not get as long a shot with the "1 iron golf clubs as you would with the similarly numbered conventional golf clubs that get shorter with each successive number. If, however you mean a single club with a changeable or rotating head to simulate the loft of different clubs, then this is illegal.
The number relates to the loft of the club and the length of the shaft. For example a 3 iron has the lowest loft and longest shaft. A 7 irons has more loft and a shorter shaft than the 3 iron.
pitching wedge
A forged iron mean it is made out of a softer material and continually stamped into shape.
offset
Fairway Wood
oversized
Ask Dustin Johnson
A low running short, usually played with a club such as a 7 iron- wedge. The ball is carried a short way and then rolls the rest of the way like a putt.
The letters TCP in golf stand for tournament players club. TCP is a network of golf courses operated by the PGA tour.
Fire and Iron Motorcycle Club 6th letter of the alphabet "Fire" 9th letter of the Alphabet "Iron"
It is the total number of golf club strokes, that a specific course was designed to be played in for 18 holes.