Hm. Ohh ... from the Mainpeak Au site.... "Description ... Auriga Mesh Extreme is lighter and more airy with a nylon rainfly". But .... "Specification ... Rainfly: PU-coated, UV-resistant, flame retardant ripstop polyester"
I dont know how I got so confused. Apologies

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That said though, while you cant use urethane rubber Seam grip on silicone treated, is there any reason you cant use the silicone compatibles on polyester Franco? American labelling, theres no ingredients contains on the Silnet tube.
Every four seconds, somewhere in the world, an Harlequin Mills and Boon is sold ... Wot ...