Replacement storm door lockset help!!

I am needing to replace a door handle on a storm door. I can not find any markings on the existing handle except on the internal lock cylinder itself it says GG 7/8". Unfortunately I am unable to find any other markings. Per the door it's self, once again I am unable to locate any type of anything to even tell me what type of door it is. I googled a Pic and it lead me to your website. Please tell me you can help I am about to just rip off the door and say no door!! Lol!! Ty appreciate it if you could assist me.