They have a damper at the end of their travel so that the tailgate won't be knocking in the fully open position. Furthermore, I was using a free delivery voucher which saved me postage cost of £8.45
These are the exact replacement part for our 2006 Citroen C4 Picasso (not Grand Picasso)
Ordered two, received a few days later in good original packaging. Fitted both within 10 mins. Thanks!