"Thick Walls" are much heavier then the other cylinders. The cylinder wall is a full 1/4" thick and is made of the highest quality Acrylic Lucite material. The end design is round and silky smooth for a highest level of conformability. Because of the weight of the “Thick Walls” cylinders they are great for those who like to have their penis stretched while pumping aka increasing the vertical pulling effect. "Thick Walls" are highly recommended for double action pumpers (Cock& Balls). 100% hand polished and handcrafted in U.S.A No exchanges or refunds for incorrect size on cylinders! 30 Days Manufacturer Defect Warranty. PUMP SOLD SEPARATLEY