Question on hose clamp size and fans

What size hose clamps should I get for 1/2 ID X 3/4 OD tubing? I was looking at the McMaster type 430 non-perforated worm clamps. They have 1/2 x 3/4 and 5/8 x 1-1/16 which are closest to the tubing size. Will the 1/2 x 3/4 fit over the 3/4OD tubing once it's on the barb? Should I go for the next larger size?
I was looking at either the Yate Loons(1350rpm, 47cfm) or the Mechatronics(1500rpm, 55cfm) for a mcr320. I hear everyone talking about the Yate Loons for a rad. Has anyone used the Mechatronics? They're listed has having a higher cfm at a lower dba than the Yate's but are they any good on a rad? Most of the high cfm, low dba fans are only good as case fans.
Thanks.

I never heard about mechatronics fans but they will louder than Yate loons. Two give aways; higher cfm and higher rpm.

As goes for clamps, I don't even know what I am buying when I am at the hardware store. I look at the tube and pick the one closes to tubing size. Make sure you pick skiny clamps

Here are the fans:
http://www.coolerguys.com/840556034032.html

The Yate Loons are proven quiet... near their stated numbers. The Mechatronics are unknown so they may or maynot be accurate numbers. You could buy one of each and see how they compare. I just go with Yate Loons because I've had success with them.

http://www.directron.com/a2368.html
http://www.directron.com/sff21e.html
http://www.directron.com/sff21f.html
http://www.directron.com/uc12eb.html

I've used both the Scythes and the Thermaltake as case fans - nice units. The Enermax is relatively new ...

Thanks, but I just wanted to know if someone has used those Mechatronics on their rad. And if the McMaster 1/2 x 3/4 type 430 worm clamps will fit on 3/4 OD tubing or should I get the next size that goes up to 1-1/16?