This is a set of 4 sound-absorbing materials: the sound-absorbing material (Shokupan) for the back of the speaker and the sound-absorbing material (Castella) for around the speaker. It can be combined with deadening sheets, etc., and further improvement in sound quality can be expected! Born from the voices of many customers! It took half a year to commercialize, and we were particular about the quality and shape! We created it by carefully selecting the thickness and material from scratch, comparing over 10 types of materials with 3 people. We created it with the intention of satisfying even the experts! [Contents] ・Shokupan (speaker back sound-absorbing material) 2 pieces Size: Approximately 200mm x 200mm x 50mm per piece ・Castella (speaker surrounding sound-absorbing material) 2 pieces Size: Approximately 25mm x 25mm x 590mm per piece [Features] ■Shokupan A high-performance sound-absorbing material developed with the optimal shape and material for the door interior environment. The ultra-thick 50mm sound-absorbing material minimizes unwanted sounds (reflected sounds) that are reflected by the iron plate, etc., and produces clear sound! ■Castella The shape and material were designed to maximize the effect even in the narrow environment between the speaker and the interior trim! The low-resilience, moist material, like Castella cake, won't damage the speaker. Touch it once and feel its gentle texture! The Shokupan & Castella set Both adopt a wave shape! This wave shape is also widely used in concert halls and music studios. By making the surface area wider than a flat shape, more reflected sound can be absorbed, and further improvement in sound quality can be expected. [Great value set!] The individual items are 3980 yen for 2 Shokupan pieces and 2480 yen for 2 Castella pieces, for a total of 6460 yen. The set is 5200 yen in total! That's over 1200 yen off! shop Kaze Kobo also sells many other products, such as headlights, fog lights, and sound quality improvement sheets, so please check out the hashtags and my page! #shopKazeKoboSoundQualityImprovementCommittee [Specs] Material: Synthetic rubber Heat resistance: 120° Cold resistance: -40° [Caution] ・Be sure to degrease and remove dust before installation. ・If there is a door beam on the back, cut the interfering part with a cutter, etc. ・Please be careful not to interfere with the power window.