A compound of formula : wherein A1, A2, A3, A4, R1, R2, G1, G2, Q1 and Q2 are as defined in claim 1; or a salt or N-oxide thereof. The brackets include engagement ends positioned on an extension member formed on the bracket body. Each one of the absorber blades comprises an absorber material distributed in the longitudinal direction, whereby a mean value of the quantity of absorber material per unit of length of the control rod is smaller in the upper part of the control rod than in the lower part thereof. Tapered products may be formed by moving the mold towards a pallet so that the pallet engages with the end liner and causes the end liner to move from the vertical position to the angled position.