As Brian isn't my really name I can admit quite openly that the average condom does tend to flap about a bit, so I thought I try these to see if they were any better and to be honest they were too tight.

But I've noticed that this site has "Width at Base" (in this case 49mm) and
"Width of shaft" (in case 49mm again), and the Durex I was buying down at Boots is 52mm, so I'm off to look for something in a 50 or 51mm. I can tell you now too loose is better than too tight, but then again you don't want it to come off, so I support the right size is right.