These TNC to N adapters come in both 11 and 18Ghz versions. The 18ghz version of these TNC to N adapters use precision N's, & precision tnc's. The 11 ghz parts use "standard" N's and TNC's, as called out in mil-specs.The precision tnc to n adapters are made of stainless steel & use the TNCA interface. The brass versions of these TNC to N adapters use brass for their bodies. The standard tnc to n adapters work well to 13ghz or so, but as the current P287 standard is set to 11ghz we want to correlate with it.