The British and Irish Lions are to award ceremonial caps for the first time.
A total of 419 living Lions players and next of kin of 416 deceased Lions will receive a one-off, hand-stitched cap that bears a unique playing number awarded only to players who have played competitively in the red shirt.
Wales star Sam Warburton, who captained the Lions in Australia five years ago and to New Zealand last summer, hailed the move.
"It feels like the missing piece of the jigsaw to add your Lions cap to go with your others, your international and your club caps," he said.
"This makes it all come flooding back, and makes you realise how prestigious a thing it is to play for the Lions."
Ronnie Dawson, the Lions' oldest living captain, added: "Playing for your country is the biggest thing that can happen to you as a young player, but if you are fortunate enough to go on and play for the Lions, it's extreme.
"It is a wonderful experience in every way. So to receive a cap marking that really completes the series."
The Lions announced that In addition to the cap, Lions players or next of kin will receive a recognition letter from Lions chairman Tom Grace and a copy of the team photograph from their tour or tours.