Tannoy Silver

Hi everyone, I'm leave in Quebec (Canada). I am novice in HIFI and I want to learn more about it. I have a pair of Tannoy Silver and I want to know more about it. My friend gave me his speakers before he died. I heard that probably I would find here Tannoy specialists. My friend gave me a pair of Electro-voice Regency cabinets and after having received these firms I opened the back of the box. I found that this was not the original speakers. I've seen are 15 inch Tannoy Silver. The issue is that the model number I found is different than anything I found on the net. Does anyone know anything about it. The model number on the speaker and the crossover that I've found is LSU/HF/15F. All information that I have found are on LSU/HF/15L.
What differnce between F and L.