The kit has alot of solid balsa, blocks few lightning holes etc. The kit is of good quality but must be 10-15 year old technology. This is one of the best Biplanes available. Mine is a kit build any now is almost 10 yrs old. I shoe horned an OS 1.08 2 stoke in mine after starting out with a .61 to a 1.2 four stroke and then to the BIG 1.08. I have flown the ARF and it handles great, a little lighter on the sticks than my kit built but both are super airplanes.