as shown more particularly in fig1 in arrays aligned with a roller hockey player 39 s leg axis 49 and foot axis 50 similarly as shown in fig7 b fig8 b fig9 b fig1 b and in fig1 the plurality of ball bearings 26 ii of the assembled apparatus in fig1 b 28 may be patterned in arrays e g rectangular arrays according to the shape of a knee landing 44 of a roller hockey goalie leg protective member 40 and as shown more particularly in fig1 in arrays aligned with a hockey player 39 s knee axis 51 which arrays may facilitate movement in e g in both forward and backward as well as lateral and semi lateral directions as shown in fig1 the assembled apparatus of fig1 a 16 may be placed on the shin area landing 39 of a roller hockey goalie leg protective member 40 with the plurality of ball bearings 26 i facing away from the landing 39 and the convex side of the apparatus 18 pointing away from the knee area landing 39 of the roller hockey goalie leg protective member 40 horizontal straps 41 may pass through the slits 22 of the rectangular indented portions 21 of the apparatus 16 and wrap around the landing 39 and the face of the goalie leg protective member 42 and around the lower leg of the goalie.