Most PV rails use a T-slot or similar channel. Before you order mid/end clamps, confirm the channel opening and the bolt head that seats inside it.
Check three dimensions: channel opening, bolt diameter (often M8), and the clamp base that sits on the rail crown. A mismatch shows up as rocking clamps or incomplete bite on the module frame.
Finish: zinc-plated for inland sites; stainless or HDG where salt or industrial humidity is expected. Name the standard in the inquiry so we quote the right hardware kit.
Send us rail cross-section drawings or photos with a scale — we will match clamp + bolt + nut sets from stock or OEM.