Use the clamps that came with the lights. I use them and they work perfectly fine. But the only downside is they only work on 1 1/2 inch trussing i believe, none the less they are exceptionally sturdy and have had my lights flown for over 3 years now
this is the clamp included, if you lost it... here is the link to order more
http://parts.americandj.com/ProductDetails.aspx?ItemNum...Line=DJ%20SPOT%20250 $32/each is pricey, but they are worth it.