Low insertion loss coaxial cable 50 ohm with 0.14db loss per meter (900Mhz measured).
 
The diameter is 10.10mm ±0.05mm. Very similar to the LMR400 which is a registered trademark and therefore much more expensive. For helium miners of all manufacturers.
 
Connection here N-MALE to RP-SMA-MALE (fits directly to many miners without an adapter)
The thinner RG58 usually have a loss of 0.325db/1m, which is not negligible over e.g. 5m.
 
Length 3m
 
Cable structure see picture.