that are on Gunbroker right now. Descriptons is :

Gun Power Ultimate Silicone High-tensile Square Section Main Spring for RWS48, RWS52 ans RWS54 ( the spring will fit in the RWS34, RWS36 and RWS38 also, but I did find the spring to be a bit overpowered for them ) - The springs were made in England in the early 90's - They are new just old inventory - I always recommended that a heavy pellet was used with this spring installed

http://www.gunbroker.com/auction/ViewItem.asp?Item=111833567

they are the old Ox springs made in the UK some years ago. A few hundred were made apparently, they didn't sell well because they pretty much sucked. The remaining inventory keeps popping up from time to time with a new name. Designed for raw power with no regard for shootability, real harsh recoil, short life, real hard to cock. Not really what you want in your rifle.