This is the lens cover that allows you to attach 9 lenses to 2 9w bar lights, or 18 lenses to 1x 18w bar light, just choose the type of lens you would require.

Includes covers, 18x lenses plus clips. 

The pictures give you an illustration of the extra intensity that you get if you use the lens option, in this picture they are using 60° lenses. You can see the difference in intensity at the centre, the light meter is set at 10 times so the centre reading is 2000 lm without lenses i.e. standard 120° spread, and this goes up to 7000 with the use of 60° lenses. Because these lights can be mounted very flexibly i.e. in amongst or very close to the growing tips, see hanging support system, and sometimes having this intensity is not necessary, but it is a great option to have as sometimes you will find it will make all the difference. This is very useful in situations where you have a plant that does not spread out much.

Must be purchased with at least 1 set of bar lights.