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LEGO Missing Piece Checker

Rule out the usual hiding places first. If the piece really is gone, check the set piece by piece and leave with the element ID LEGO asks for, or a link to buy the part.

Ultrasonic Showdown

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70171 Ultrasonic Showdown

157 pieces in 70 part and color combinations, plus 2 minifigures.

The piece count includes the 30 parts inside the set's minifigures, which this inventory lists separately. Spare parts are counted in neither figure.

Before you call it missing

Builders who report a missing piece often find it in one of these places. Tick each one off as you look.

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Piece checklist

Black 50 pieces

  • Bracket 1 x 2 - 1 x 2 Inverted Black Part 99780 Element 6020193 ×4
  • Bracket 1 x 2 - 2 x 4 Black Part 93274 Element 6118829 or 4616245 ×2
  • Brick Round 2 x 2 Truncated Cone Black Part 98100 Element 4653822 ×2
  • Brick Round 2 x 2 [Grill] Black Part 92947 Element 6024730 ×2
  • Brick Round 4 x 4 Centre Hole Black Part 87081 Element 4558957 ×2
  • Brick Round Corner 6 x 6 with 33° Slope and Facet Cutout Black Part 95188 Element 6605464 or 6337391 ×2
  • Brick Sloped 18° 2 x 1 x 2/3 with 4 Slots / Grate Black Part 61409 Element 4541191 ×2
  • Brick Sloped 30° 1 x 1 x 2/3 (Cheese Slope) Black Part 54200 Element 4504382 or 4287159 ×2
  • Brick Special 1 x 1 with Stud on Side and Conductive Element on Opposite Side Black Part 15411 Element 6103777 or 6096747 ×2
  • Brick Special 1 x 2 with Vertical Clip [Open O Clip] Black Part 30237b Element 6330197 or 6092876 ×1
  • Brick Special 1 x 2 x 2/3 with Studs on Sides Black Part 4595 Element 6681661 or 4523339 ×1
  • Brick Wedged, Curved 4 x 4 No Top Studs Black Part 47753 Element 4219107 ×2
  • Brick Wedged, Sloped 4 x 2 Triple Left Black Part 43710 Element 6040297 or 4180413 ×1
  • Brick Wedged, Sloped 4 x 2 Triple Right Black Part 43711 Element 6040298 or 4180423 ×1
  • Engine, Large Black Part 43121 Element 4295395 ×1
  • Equipment Radio [Extended Handle, Expanded Speaker Grille] Black Part 19220 Element 6170545 or 6100054 ×1
  • Hinge Brick 1 x 2 Base Black Part 3937 Element 393726 ×2
  • Plate 4 x 4 Black Part 3031 Element 4243819 or 303126 ×2
  • Plate Special 1 x 2 with Clips Horizontal [Open O Clips] Black Part 60470b Element 6310268 or 4556158 ×1
  • Tail Shuttle Black Part 6239 Element 6093011 or 4531192 ×2
  • Technic Pin with Friction Ridges Lengthwise and Center Slots Black Part 2780 Element 4121715 or 278026 ×4
  • Tile Round 2 x 2 with Bottom Stud Holder Black Part 14769 Element 6070695 ×1
  • Wedge Plate 3 x 2 Left Black Part 43723 Element 4180536 ×1
  • Wedge Plate 3 x 2 Right Black Part 43722 Element 4180508 ×1
  • Wedge Plate 4 Stud 45° Angle Plate Black Part 15706 Element 6054852 ×4
  • Wedge Plate 6 x 12 Left Black Part 30355 Element 4143180 ×1
  • Wedge Plate 6 x 12 Right Black Part 30356 Element 6394881 or 4143181 ×1
  • Wedge Plate 8 x 3, 22° Left Black Part 50305 Element 4251394 ×1
  • Wedge Plate 8 x 3, 22° Right Black Part 50304 Element 4251393 ×1

Trans-Orange 27 pieces

  • Cone 1 x 1 [Top Groove] Trans-Orange Part 59900 Element 6514017 or 6172233 ×2
  • Plate Round 1 x 1 with Solid Stud Trans-Orange Part 6141 Element 6514059 or 6240227 ×25

Dark Bluish Gray 23 pieces

  • Brick 2 x 2 Dark Bluish Gray Part 3003 Element 4211060 ×1
  • Brick Curved 2 x 2 x 2/3 Two Studs and Curved Slope End Dark Bluish Gray Part 47457 Element 4218696 ×1
  • Brick Sloped 45° 2 x 2 Dark Bluish Gray Part 3039 Element 4211054 ×1
  • Plate 1 x 3 Dark Bluish Gray Part 3623 Element 4211133 ×2
  • Plate 2 x 2 Dark Bluish Gray Part 3022 Element 4211094 ×1
  • Plate 2 x 4 Dark Bluish Gray Part 3020 Element 4211065 ×5
  • Plate 2 x 6 Dark Bluish Gray Part 3795 Element 4211002 ×1
  • Plate Special 2 x 2 with Groove and Center Stud (Jumper) Dark Bluish Gray Part 87580 Element 6126083 or 4565322 ×2
  • Technic Axle 8 with Stop Dark Bluish Gray Part 55013 Element 4499858 ×2
  • Technic Brick 1 x 2 [1 Pin Hole] Dark Bluish Gray Part 3700 Element 4211111 ×3
  • Technic Brick 1 x 4 [3 Pin Holes] Dark Bluish Gray Part 3701 Element 4213607 or 370127 ×2
  • Wedge Plate 3 x 3 Cut Corner Dark Bluish Gray Part 2450 Element 4210897 ×2

White 23 pieces

  • Bracket 1 x 2 - 1 x 2 White Part 99781 Element 6552141 or 6548275 ×3
  • Brick Sloped 18° 2 x 1 x 2/3 with 4 Slots / Grate White Part 61409 Element 6552142 or 6023804 ×1
  • Brick Sloped 45° 2 x 1 with Bottom Pin White Part 3040b Element 6552115 or 4121932 ×2
  • Launcher, Weapon Rapid Shooter Six Barrel, 3 Fingers White Part 18588 Element 6114966 ×2
  • Plate 2 x 3 White Part 3021 Element 6550136 or 302101 ×4
  • Plate 4 x 4 Corner White Part 2639 Element 6552129 or 4508662 ×2
  • Technic Brick 1 x 1 with Pin Hole White Part 6541 Element 6609542 or 654101 ×2
  • Tile 1 x 6 with Groove White Part 6636 Element 6548296 or 663601 ×2
  • Turntable 4 x 4 Square Base, Locking White Part 61485 Element 6619301 or 4611927 ×2
  • Weapon Gun / Pistol Two Barrel, 10 Ribs White Part 95199 Element 6081466 ×1
  • Wedge Plate 3 x 2 Left White Part 43723 Element 6552121 or 4179875 ×1
  • Wedge Plate 3 x 2 Right White Part 43722 Element 6552120 or 4179874 ×1

Trans-Light Blue 20 pieces

  • Brick Curved 2 x 2 with Lip, No Studs Trans-Light Blue Part 30602 Element 6171718 or 6064345 ×3
  • Brick Sloped 30° 1 x 1 x 2/3 (Cheese Slope) Trans-Light Blue Part 54200 Element 6245277 or 6073445 ×2
  • Dish 2 x 2 Inverted [Radar] Trans-Light Blue Part 4740 Element 6580378 or 6245307 ×1
  • Plate 1 x 2 Trans-Light Blue Part 3023 Element 6514007 or 6240222 ×9
  • Tile Round 1 x 1 Trans-Light Blue Part 98138 Element 6514192 or 6274739 ×4
  • Windscreen 6 x 4 x 2 1/3 Bubble Canopy with Handle Trans-Light Blue Part 87752 Element 6507953 or 6254264 ×1

Light Bluish Gray 5 pieces

  • Hinge Brick 2 x 2 Top Plate Thin Light Bluish Gray Part 6134 Element 4211881 ×2
  • Launcher Trigger, Weapon Rapid Shooter, Flat Axle Hole Light Bluish Gray Part 18587 Element 6097090 ×2
  • Plate 2 x 8 Light Bluish Gray Part 3034 Element 4211406 ×1

Blue 4 pieces

  • Brick Special 1 x 1 with Headlight Blue Part 4070 Element 407023 ×2
  • Technic Pin 1/2 without Friction Ridges Blue Part 4274 Element 4143005 ×2

Red 2 pieces

  • Bracket 1 x 2 - 2 x 2 Inverted Red Part 99207 Element 6001806 ×2

Pearl Gold 1 piece

  • Plate Special 1 x 2 with 1 Stud with Groove and Inside Stud Holder (Jumper) Pearl Gold Part 15573 Element 6092594 ×1

Trans-Red 1 piece

  • Tile 1 x 2 with Groove Trans-Red Part 3069b Element 6514220 or 6251290 ×1

[No Color/Any Color] 1 piece

  • Sticker Sheet for Set 70171-1 [No Color/Any Color] Part 21670 Element 6117695 ×1

Minifigures 2 figures

  • Agent Curtis Bolt Minifigure, checked as a whole figure ×1
  • Professor Brainstein with Mechanical Spider Legs Minifigure, checked as a whole figure ×1

Tick each piece as you find it, or mark it missing.

When a piece really is missing

Ask LEGO

LEGO takes requests for pieces missing from a new set through its customer service site. The form asks for the set number and each piece's element ID, the number printed beside the piece in the parts list at the back of the instructions. This checker lists both.

Request a replacement from LEGO

Buy the piece

Mark a piece missing and your list links it to an eBay search for that part, which also covers pieces from older or second-hand sets.

Keep a record

Copy or download your missing list (the CSV opens in any spreadsheet), or print the whole checklist and tick pieces off on paper. Your marks stay in this browser, so you can check a big set over several sittings.

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