right you will have to excuse me because am a woman and used to being on the top end of the sink not the bottom, my question I need a waste trap the one I want is sold out at B&q, I saw a similar one at screwfix, are these pretty much universal fitting, I asked the man in the shop but he said just check before I buy ??? first pic is the one I wanted the second is the one Im thinking of getting ..what do I need to check to make sure it fits...