TST 507 here George. Screw on caps; color monitor; repeater; constant monitoring of temp/pressure. I've never had a battery go dead in about 5 years but I have replaced them once (maybe twice??
). Towed for decades without one and never gave it a minutes thought then we had the blowout that zapped us for 7k. Now, between it and upgraded tires they take lots of worry out of my brain.