alright lads,so ive just bought a air arms s400 classic,the shop i bought it from had 2 pumps one for 129£ and one for 189£,ive looked on fleabay and theres some for 55£.after watching demonstration how to use pump for s400 on youtube,the pumps on look to have different fitting to the one on youtube,so which pump should i buy please ???.ive been a springer man for years so no idea about pcp guns.if somone can put item number off for pump i need that would be a big help.cheers lads