Thermowell help

[DeadFall]

I'm looking for a thermowell, ideally 300mm long so I can drop it in from the top to avoid drilling out the fv sides, that will fit the pre-wired DS18B20 probes common on ebay. They say they're 6mm wide but they won't fit into a 6mm hole I drilled (7mm is fine) and I've just sent back a thermowell that was advertised as being 7mm ID. The one I bought is 6mm and I was using a self wired sensor, but the condensation in the tube has killed the sensor so I bought some water-proof pre-wired jobs. I've found http://www.brewershardware.com/Straight ... hermowells who will deliver to the UK for a postage fee that's twice the price of the thermowell. (they have 1/4 inch and .305 available, the 1/4 inch feels too tight, but the .305 too loose). I don't have calipers to measure the probe width, but I'd guess they're around 6.5mm. Any ideas?

[DeadFall]

I think I've found a proper 6mm bs18b20 probe sensor - http://www.ebay.co.uk/itm/111776844887 I'll report back!