I ordered "O" rings which were ideal for the job and it was one of the few sites that stocked my specific size. I don't know why they offer the RMSD service at £7.99 as instead of taking 1 day to arrive it took 2 days which defeated the object. There is a warning that this is not a guaranteed service? work that one out. It wasn't delivered by the seller to Royal Mail until late evening approx. 19:45, hence the 2 day delivery. I would advice anyone requiring a 24 service not to use the RMSD option. Otherwise okay.