1. SMOOTH LOCK (SL)
- The 1/2” SL uses 2” of metal from the overall cut size.
- The 3/4” SL uses 3” of metal from the overall cut size
- The 3/4” SL is user friendly and allows more room for error.
2. PITTSBURGH LOCK (PL)
- The PL uses 2 inches of metal.
![3](https://rvsiding.com/wp-content/uploads/2016/10/3.png)
![33](https://rvsiding.com/wp-content/uploads/2016/10/33.png)
3. MOCK PITTSBURGH LOCK (ML)
- The ML has become more popular over the past few years.
- It is located at the bottom of units, 1″ of material is required to manufacture the ML.
![4](https://rvsiding.com/wp-content/uploads/2016/10/4.png)
![44](https://rvsiding.com/wp-content/uploads/2016/10/44.png)
4. NO LOCK (NL)
- This indicates that no lock is needed and just the rough edge is left.
![5](https://rvsiding.com/wp-content/uploads/2016/10/5.png)
5. HEM LOCK (HL)
- The HL is utilized for pieces which may require a 1/2 inch return to allow the finished edge to be smooth rather than raw. (as is the case when no lock is applied.)
- The standard HL has a 1/2 inch return as it is the minimum amount needed to manufacture the HL, however returns of 3/4″, 1″ etc., are also possible.
![6](https://rvsiding.com/wp-content/uploads/2016/10/6.png)
6. ROOF LOCK
- Roof lock locks two or more pieces together with only a small seam.
![7](https://rvsiding.com/wp-content/uploads/2016/10/7.png)